Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. 
Exactly 50 years ago, humanity stepped foot on the surface of the Moon for the first time. It was a miracle, and one made so powerful because it was so very unlikely. It was hailed as an incredible success. But the chance of failure was such that authorities had to prepare for the possibility of losing the astronauts. Those preparations offer a humbling insight into how risky that mission was, and how high the stakes were. Probably the most potent document from those preparations is the speech that would have been used to hail the bravery of the astronauts as they were left to their death on the Moon.
It was written to announce to the world that the astronauts had been lost, and that the Moon mission was a failure. After it was read, the two astronauts would be given a ceremony something like the burial at sea, but one entirely without precedent. The document was hidden for many years – unused, it was "quietly tucked away into the record" after the astronauts returned home, as the National Archive that now holds it notes. But over time it became public, after being revealed by the man who wrote it, and is now available for the public to read.
It was prepared in the case that the astronauts and their moon lander failed to get back to the main craft that was floating around in the Moon's orbit ready to bring them home, and contained Neil Armstrong and Buzz Aldrin's colleague Michael Collins. In that case, it was most likely that those pioneering explorers would not lose their lives in a single spectacular moment. Instead, they would most likely be stranded, stuck 250,000 miles from Earth with no way of getting back home. "If they couldn't get back safely, they'd have to be abandoned on the moon, left to die there," speechwriter William Safire said in 1999. "The men would either have to starve to death or commit suicide."
In the end, and despite some very anxious moments, the crew would explore the lunar surface and come back down safely. That meant that, instead of announcing their loss, Nixon could instead share in the astronaut's success. In one of the most famous moments of the mission, he spoke to them in a phone call that was beamed around the world. He recognised the triumph of their achievement, and wished them safety for their return.

What did Nixon do after the crew landed safely?

Plants and animals will find it difficult to escape from or adjust to the effect of global warming, Scientists have already observerd shifts in the lifecycles of many plants and animals, such as flowers blooming earlier and birds hatching earlier in the spring. Many species have begun shifting where they live or their annual migration patterns due to warmer temperatures.
With further warming, animals will tend to migrate toward the poles and up mountainsides toward higher elevations. Plants will also attempt to shift their ranges, seeking new areas as old habitats grow too warm. In many places, however, human development will prevent these shifts. Species that find cities or farmland blocking their way north or south may become extinct. Species living in unique ecosystems, such as those found in polar and mountantop regions, are especially at risk because migration to new habitats is not possible. For example, polar bears and marine mammals in the Arctic are already threatened by dwindling sea ice but have nowhere farther to go.
Projecting species extinction due to global warming is extremely difficult. Some scientists have estimated that 20 to 50 percent of species could be committed to extiction with 2 to 3 Celsius degrees of further warming. The rate of warming, not just the magnitude, is extremely important for plants and animals. Some species and even entire ecosystems, such as certain types of forest, many not be able to adjust quickly enough and may disappear.
Ocean ecosystems, especially fragile ones like coral reefs, will also be affected by global warming. Warmer ocean temperatures can cause coral to "bleach", a state which if prolonged will lead to the death of the coral. Scientists estimate that even 1 Celsius degree of additional warming could lead to widespread bleaching and death of coral reefs around the world. Also increasing carbon dioxide in the atmosphere enters the ocean and increases the acidity of ocean waters. This acidification furter stresses ocean ecosystems.

What does the passage mainly discuss?

Very few people in the modern world obtain their food supply by hunting and gathering in the natural environment surrounding their homes. This method of harvesting from nature’s provision is the oldest known subsistence strategy and has been practised for at least the last two million years. It was, indeed, the only way to obtain food until rudimentary farming and the domestication of wild animals were introduced about 10,000 years ago.
Because hunter-gatherers have fared poorly in comparison with their agricultural cousins, their numbers have dwindled, and they have been forced to live in marginal environments, such as deserts and arctic wastelands. In higher latitudes, the shorter growing seasons have restricted the availability of plant life. Such conditions have caused a greater dependence on hunting, and on fishing along the coasts and waterways. The abundance of vegetation in the lower latitudes of the tropics, on the other hand, has provided a greater opportunity for gathering a variety of plants. In short, the environmental differences have restricted the diet and have limited possibilities for the development of subsistence societies.
Contemporary hunter-gatherers may help us understand our prehistoric ancestors. We know from the observation of modern hunter-gatherers in both Africa and Alaska that a society based on hunting and gathering must be very mobile. While the entire community camps in a central location, a smaller party harvests the food within a reasonable distancefrom the camp. When the food in the area has become exhausted, the community moves on to exploit another site. We also notice seasonal migration patterns evolving for most hunter-gatherers, along with a strict division of labor between the sexes. These patterns of behavior may be similar to those practised by mankind during the Paleolithic Period.

According to the author, most contemporary and prehistoric hunter-gatherers share ..................

Read the following passage and choose the best answer for each blank.

The World Wide Fund for Nature (WWF) is an international (26) _____- governmental organization for the (27) _____, research, and restoration of the environment. The organization was (28) _____ as a charitable trust on September 11, 1961, in Morges, Switzerland, under the name World Wildlife Fund. It was an initiative of Julian Huxley and Max Nicholson.It is the world's largest independent conservation organization with over 5 million (29) _____ worldwide, working in more (30) _____ 90 countries, supporting 100 conservation and environmental projects around the world. It is a charity, with (31) ____ 9% of its funding coming from voluntary (32) ___ by private individuals and businesses.The group says its mission is "to halt and reverse the (33) _____ of our environment". Currently, much of its work focuses on the conservation of three biomes that contain most of the world's biodiversity: forests, freshwater ecosystems, and oceans and coasts. Among other issues, it is also concerned (34) _____ endangered species, pollution, and climate change. The organization (35) ____ more than 20 field projects worldwide. In the last few years, the organization set up offices and operations around the world.

(26) _____

Chọn từ thích hợp điền vào chỗ trống:

THE THREAT TO THE ENVIRONMENT

Nowadays people are more aware that wildlife all over the world is in danger. Many (1)________of animals are threatened, and could easily become (2)______ if we do not make an effort to protect them. There are many (3)_______ for this. In some cases, animals are hunted for their fur or for othervaluable parts of their bodies. Some birds, such as parrots, are caught (4)________and sold as pets. For many animals and birds, the problem is that their habitat - the (5)________where they live - is disappearing. More (6)________is used for farms, for houses or industry, and there are fewer open (7)________than there once were. Farmers use powerful chemicals to help them grow better (8)________, but these chemicals pollute the environment and (9)________wildlife. The most successful animals on earth - human beings - will soon be the only Ones left, unless we can (10)________this problem.

(7)________

Reading to oneself is a modern activity which was almost unknown to the scholars of the classical and medieval worlds, while during the fifteenth century the term "reading" undoubtedly meant reading aloud. Only during thenineleenthcenturydid silent reading become commonplace.
One should be wary, however, of assuming that silent reading came about simply because reading aloud was a distraction to others. Examinations of factors related to the historical development of silent reading have revealed that it became the usual mode  of reading for most adults mainly because the tasks themselves changed in character.
The last century saw a steady gradual increase in literacy and thus in the number of readers. As the number of readers increased, the number of potential listeners declined and thus there was some reduction in the need to read aloud. As reading for the benefit of listeners grew less common, so came the flourishing of reading as a private activity in such public places as libraries, railway carriages and offices, where reading aloud would cause distraction to other readers.
Towards the end of the century, there was still considerable argument over whether books should be used for information or treated respectfully and over whether the reading of  materials such as newspapers was in some way mentally weakening. Indeed, this argument remains with us still in education. However, whatever its virtues, the old shared literacy  culture had gone and was replaced by the printed mass media on the one hand and by books and periodicals for a specialised readership on the other.
By the end of the twentieth century, students were being recommended to adopt attitudes to books and to use reading skills which were inappropriate, if not impossible, for the oral reader. The social, cultural and technological changes in the century had greatly altered what the term "reading" implied.

The development of silent reading during the last century indicated..........................

Reading to oneself is a modern activity which was almost unknown to the scholars of the classical and medieval worlds, while during the fifteenth century the term "reading" undoubtedly meant reading aloud. Only during thenineleenthcenturydid silent reading become commonplace.
One should be wary, however, of assuming that silent reading came about simply because reading aloud was a distraction to others. Examinations of factors related to the historical development of silent reading have revealed that it became the usual mode  of reading for most adults mainly because the tasks themselves changed in character.
The last century saw a steady gradual increase in literacy and thus in the number of readers. As the number of readers increased, the number of potential listeners declined and thus there was some reduction in the need to read aloud. As reading for the benefit of listeners grew less common, so came the flourishing of reading as a private activity in such public places as libraries, railway carriages and offices, where reading aloud would cause distraction to other readers.
Towards the end of the century, there was still considerable argument over whether books should be used for information or treated respectfully and over whether the reading of  materials such as newspapers was in some way mentally weakening. Indeed, this argument remains with us still in education. However, whatever its virtues, the old shared literacy  culture had gone and was replaced by the printed mass media on the one hand and by books and periodicals for a specialised readership on the other.
By the end of the twentieth century, students were being recommended to adopt attitudes to books and to use reading skills which were inappropriate, if not impossible, for the oral reader. The social, cultural and technological changes in the century had greatly altered what the term "reading" implied.

The writer of this passage is attempting to ....................

It's often said that we learn things at the wrong time. University students frequently do the minimum of work because they're crazy about a good social life instead. Children often scream before their piano practice because it’s so boring. They have to be given gold stars and medals to be persuaded to swim, or have to be bribed to take exams. But the story is different when you’re older.
Over the years, I've done my share of adult learning. At 30, I went to a college and did courses in History and English. It was an amazing experience. For starters, I was paying, so there was no reason to be late - I was the one frowning and drumming my fingers if the tutor was late, not the other way round. Indeed, if I could persuade him to linger for an extra five minutes, it was a bonus, not a nuisance. I wasn't frightened to ask questions, and homework was a pleasure not a pain. When I passed an exam, I had passed it for me and me alone, not for my parents or my teachers. The satisfaction I got was entirely personal
Some people fear going back to school because they worry that their brains have got rusty. But the joy is that, although some parts have rusted up, your brain has learnt all kinds of other things since you were young. It has learnt to think independently and flexibly and is much better at relating one thing to another. What you lose in the rusty department, you gain in the maturity department.
In some ways, age is a positive plus. For instance, when you're older, you get less frustrated. Experience has told you that, if you're calm and simply do something carefully again and again, eventually you'll get the hang of it. The confidence you have in other areas - from being able to drive a car, perhaps - means that if you can’t, say, build a chair instantly, you don't, like a child, want to destroy your first pathetic attempts. Maturity tells you that you will, with application, eventually get there.
I hated piano lessons at school, but I was good at music. And coming back to it, with a teacher who could explain why certain exercises were useful and with musical concepts that, at the age of ten, I could never grasp, was magical. Initially, I did feel a bit strange, thumping out a piece that I'd played for my school exams, with just as little comprehension of what the composer intended as I'd had all those years before. But soon, complex emotions that I never knew poured out from my fingers, and suddenly I could understand why practice makes perfect.

 It is implied in the last paragraph that when you learn later in life, you ...........................

Read the passage and choose the best answer to compete each of the statements that follow
The hippopotamus is the third largest land animal, smaller only than the elephant and the rhinoceros. Its name comes from two Greek words which mean "river horse". The long name of this animal is often shortened to the easier to handle term "hippo."
The hippo has a natural affinity for the water. It does not float on top of the water; instead, it can easily walk along the bottom of a body of water. The hippo commonly remains underwater for three to five minutes and has been known to stay under for up to half an hour before coming up for air.
In spite of its name, the hippo has relatively little in common with the horse and instead has a number of interesting similarities in common with the whale. When a hippo comes up after a stay at the bottom of a lake or river, it releases air through a blowhole, just like a whale. In addition, the hippo resembles the whale in that they both have thick layers of blubber for protection and they are almost completely hairless.

The passage States that one way in which a hippo is similar to a whale is that_____

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions.

Successful students often do the following while studying. First, they have an overview before reading. Next, they look for important information and pay greater attention to it (which often needs jumping forward or backward to process information). They also relate important points to one another. Also, they activate and use their prior knowledge. When they realize that their understanding is not good, they do not wait to change strategies. Last, they can monitor understanding and take action to correct or "fix up" mistakes in comprehension.

Conversely students with low academic achievement often demonstrate ineffective study skills. They tend to assume a passive role in learning and rely on others (eg, teachers, parents) to monitor their studying, for example, low achieving students often do not monitor their understanding of content they may not be aware of the purpose of studying, and they show little evidence of looking back, or employing "fix-up strategies to fix understanding problems.

Students who struggle with learning new information seem to be unaware that they must extent effort beyond simply reading the content to understand and remember it. Children with learning disabilities do not plan and judge the quality of their studying. Their studying may be disorganized. Students with learning problems face challenges with personal organization as well. They often have difficulty keeping track of materials and assignments, following directions, and completing work on time. Unlike good studiers who employ a variety of study skills in a flexible yet purposeful manner, low-achieving students use a restricted range of study skills. They cannot explain why good study strategies are important for learning, and they tend to use the same, often ineffective study approach for all learning tasks, ignoring task content, structure or difficulty.

What is the topic of the passage?

Choose the letter A, B, C or D to answer these following questions:
Alligators have always been the most dangerous predators of the Florida Everglades, but their long-held position is now being challenged by a growing population of Burmese pythons.
The Burmese python, a giant snake measuring up to 20 feet long and weighing up to 200 pounds, is very popular among exotic pet owners. However, as the dead snakes grow, they become more difficult to cage and handle. To avoid dealing with the snakes, the owners irresponsibly release them into the wild. Since the Everglades is quietly similar to the python's native environment of Southeast Asia, they survive and prosper without difficulty.
The issue with the Burmese pythons is their choice of meals. They eat alligators and endangered birds, which creates strain on an already fragile ecosystem. Recently a 13-foot long Burmese python was found with a 5-foot alligator bursting from its stomach. The python died tried to eat the alligator but a larger one would have easily won the struggle. With over 30,000 Burmese pythons now living over the Everglades, a solution to stop this invasive species is necessary. If the pythons are left unchecked, there is a strong possibility they will wipe out a variety of species needed for the functioning of the Everglades ecosystem.

Why do Burmese pythons develop and prosper in a simple and easy way?

Choose the best answer

No more polar bear?

We all know that the Earth is growing warmer and warmer. This problem is called “global warming”. We also know that global warming is causing a lot of problems. Ocean levels are getting higher and higher. Because ocean levels are getting higher, storms are getting stronger and stronger. This list of problems goes on and on.

Animals are suffering a lot because of global warming. Polar bears are suffering more than most animals. This is because polar bears live in the North Pole. In the North Pole, global warming is making ice melt. Polar bears hunt from large pieces of floating ice. They jump off the ice and hunt for food. Polar bears have to swim and find these floating pieces of ice. These days, they have to swim farther to find the floating ice. Many of them don’t have enough energy. They get too tired, and they die in the water.

Polar bears are suffering because of other problems, too. Pollution makes their water dirty. Many countries go to the North Pole to look for oil and gas, and they damage the environment of the bears. In addition, when ships sail through the North Pole, they cause a lot of damage. Finally, people hunt and kill too many polar bears. However, melting ice is definitely the biggest problem.

Right now, there are about 25,000 polar bears in the world. If global warming continues, there may be only about 12,000 in the year 2050. By the year 2080, that number might be much smaller.

It is important to study polar bears. When we learn about polar bears, we also learn about the health of the North Pole. If polar bears are doing well, then the environment in the North Pole is probably healthy. If polar bears are suffering then there are probably serious problems in the North Pole.

Right now, governments around the world are working to help polar bears. There are new laws that protect polar bears. However, if global warming continues to get worse, polar bears may disappear forever.

What is the biggest problem for polar bears?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. 
More than 200 reindeer have died of starvation on the Norwegian archipelago of Svalbard, with scientists blaming their deaths on climate change. The wild deer carcasses were found on the Arctic islands this summer by researchers from the Norwegian Polar Institute (NPI), which said it had never logged so many deaths at once in 40 years of monitoring the animals’ population level. “It’s scary to find so many dead animals,” project leader Ashild Onvik Pedersen told state broadcaster NRK. “This is an example of how climate change affects nature. It is just sad.”
Svalbard’s capital Longyearbyen, the northernmost town on earth, is thought to be warming quicker than any other settlement on the planet, climate scientists warned earlier this year. The milder temperatures in the region led to unusually heavy rainfall in December, leaving a thick layer of ice when the precipitation froze. This meant the reindeer could not dig through the hardened tundra to reach the vegetation they graze on in their usual pastures, the NPI said. Svalbard’s reindeer have been observed eating seaweed and kelp when food is scarce, but these are less nutritious and cause them stomach problems.
A relatively high number of calves born last year increased the death toll, as the youngest and weakest are often the first to die in harsh conditions. “Some of the mortality is natural because there were so many calves last year. But the large number we see now is due to heavy rain, which is due to global warming,” said Ms Onvik Pedersen.
A team of three scientists spent 10 weeks investigating population of the Svalbard reindeer earlier this year. Researchers warned the decline of reindeer would cause unwanted plant species, currently kept in check by the animals’ grazing, to spread across Arctic ecosystems in Europe, Asia and North America.
Arctic reindeer and caribou populations have declined 56 per cent in the last two decades, a report by the National Oceanic and Atmospheric Administration said last year. The report said food security was partly to blame for falling herd numbers, while warmer summers could also put the animals at greater risk of diseases spread by flies and parasites. The average temperature in Longyearbyen has risen by 3.7C since 1900, more than three times the global average increase of about 1C. In 2016, the entrance to the town’s “Doomsday” seed vault – which stores specimens of almost all the world’s seeds – was flooded following heavy rainfall.

Which statement is TRUE according to the last paragraphs?

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks.
Engineers have dreaming of an underwater link between Britain and France (35)_____1802. Finally in 1994 the Channel Tunnel ( nicknamed "The Chunnel" by the English) was (36)______ opened.
This fifteen billion dollar project took seven years to (37)_____. It is about 50 km long and built 45metres under the seabed .The trains which go through the Chunnel can travel at up 300 km/h due to the (38)_______electrical system.
The journey from London to Paris via the Chunnel takes just three hours. It is also (39)______ for drivers since they can load their cars onto the trains. They don't need to book in (40)______ , as trains (41)_______every few minutes. However, while on the train, there isn't much to do and many (42)_________ the Chunnel for this (43)________ the ferries , there is no duty-free shopping , no videogame parlou or refreshment stand (44)________can you look outside and enjoy the view . As a result, many would find the Chunnel unappealing and would take the ferry instead.
(38).......................................... 
 

Choose the letter A, B, C or D to complete the passage below

An endangered species is an animal or plant that's considered at …..(1)… of extinction. A species can be listed as endangered at the state, federal, and international level. On the federal level, the endangered species list is managed …..(2)…. the Endangered Species Act.

The Endangered Species Act (ESA) was ….. (3)…. by Congress in 1973. Under the ESA, the federal government has the responsibility to protect endangered species (species that are likely to become extinct throughout all or a large portion of their range), threatened species (species that are likely to become endangered in the near future), and critical habitat (areas vital to the survival of endangered or threatened species).

The Endangered Species Act has lists of protected plant and animal species….(4)….. nationally and worldwide. When a species is given ESA protection, it is said to be a "listed" species. Many additional species are evaluated for possible protection under the ESA, and they …..(5)…called “candidate” species.

(5) ..............

Choose the best answer

The World Wide Fund for Nature (WWF) is an international (1) ____ governmental organization for the (2) ____, research, and restoration of the environment. The organization was (3) ____ as a charitable trust on September 11, 1961, in Morges, Switzerland, under the name World Wildlife Fund. It was an initiative of Julian Huxley and Max Nicholson. It is the world's largest independent conservation organization with over 5 million (4) ____ worldwide, working in more (5) ____ 90 countries, supporting 100 conservation and environmental projects around the world. It is a charity, with (6) ____ 9% of its funding coming from voluntary, (7) ____ by private individuals and businesses.

The group says its mission is "to halt and reverse the (8) ____ of our environment". Currently, much of its work focuses on the conservation of three biomes that contain most of the world's biodiversity: forests, freshwater ecosystems, and oceans and coasts. Among other issues, it is also concerned (9) ____ endangered species, pollution, and climate change. The organization (10) ____ more than 20 field projects worldwide. In the last few years, the organization set up offices and operations around the world.

(10) ____

Read the passage and choose the best answer to compete each of the statements that follow
The hippopotamus is the third largest land animal, smaller only than the elephant and the rhinoceros. Its name comes from two Greek words which mean "river horse". The long name of this animal is often shortened to the easier to handle term "hippo."
The hippo has a natural affinity for the water. It does not float on top of the water; instead, it can easily walk along the bottom of a body of water. The hippo commonly remains underwater for three to five minutes and has been known to stay under for up to half an hour before coming up for air.
In spite of its name, the hippo has relatively little in common with the horse and instead has a number of interesting similarities in common with the whale. When a hippo comes up after a stay at the bottom of a lake or river, it releases air through a blowhole, just like a whale. In addition, the hippo resembles the whale in that they both have thick layers of blubber for protection and they are almost completely hairless.

The possessive "Its" in line 1 refers to________________

Read the following passage and choose the best answer for each blank.

The World Wide Fund for Nature (WWF) is an international (26) _____- governmental organization for the (27) _____, research, and restoration of the environment. The organization was (28) _____ as a charitable trust on September 11, 1961, in Morges, Switzerland, under the name World Wildlife Fund. It was an initiative of Julian Huxley and Max Nicholson.It is the world's largest independent conservation organization with over 5 million (29) _____ worldwide, working in more (30) _____ 90 countries, supporting 100 conservation and environmental projects around the world. It is a charity, with (31) ____ 9% of its funding coming from voluntary (32) ___ by private individuals and businesses.The group says its mission is "to halt and reverse the (33) _____ of our environment". Currently, much of its work focuses on the conservation of three biomes that contain most of the world's biodiversity: forests, freshwater ecosystems, and oceans and coasts. Among other issues, it is also concerned (34) _____ endangered species, pollution, and climate change. The organization (35) ____ more than 20 field projects worldwide. In the last few years, the organization set up offices and operations around the world.

(32) _____

Read the following passage and choose among A, B, C or D the correct answer to each of the questions.

In my experience, freshmen today are different from those I knew when I started as a counselor and professor 25 years ago. College has always been demanding both academically and socially. But students now are less mature and often not ready for the responsibility of being in college.

It is really too easy to point the finger at parents who protect their children from life's obstacle. Parents, who handle every difficulty and every other responsibility for their children writing admission essays to picking college courses, certainly may contribute to their children's lack of coping strategies. But we can look even more broadly to the social trends of today.

How many people do you know who are on medication to prevent anxiety or depression? The number of students who arrive at college already medicated for unwanted emotions has increased dramatically in the past 10 years. We, as a society, don't want to "feel" anything unpleasant and we certainly don't want our children to "suffer".

The resulting problem is that by not experiencing negative emotions, one does not learn the necessary skills to tolerate and negotiate adversity. As a psychologist, I am well aware of the fact that some individuals suffer from depression and anxiety and can benefit from treatment, but I question the growing number of medicated adolescents today.

Our world is more stressful in general because of the current economic and political realities, but I don't believe that the college experience itself is more intense today than that of the past 10 years. What I do think is that many students are often not prepared to be young "adults" with all the responsibilities of life.

What does this mean for college faculty and staff? We are required to assist in the basic parenting of these students - the student who complains that the professor didn't remind her of the due date for an assignment that was clearly listed on the syllabus and the student who cheats on an assignment in spite of careful instructions about plagiarism.

As college professors, we have to explain what it means to be an independent college student before we can even begin to teach. As parents and teachers we should expect young people to meet challenges. To encourage them in this direction, we have to step back and let them fail and pick themselves up and move forward. This approach needs to begin at an early age so that college can actually be a passage to independent adulthood.

According to the writer, failure in life and less support from parents will ____.

Đọc đoạn văn sau và chọn đáp án đúng cho mỗi câu hỏi:

Species that belong to an area are said to be native species. Typically, they have been part of a given biological landscape for a long period, and they are well adapted to the local environment and to the presence of other native species in the same general habitat. Exotic species are interlopers, foreign elements introduced intentionally or accidentally into new settings through human activities. In one context an introduced species may cause no obvious problems and may, over time, be regarded as being just as "natural" as any native species in the same habitat. In another context, exotics may seriously disrupt delicate ecological balances and create a cascade of unintended consequences. The worst of these unintended consequences arise when introduced species put native species in destruction by preying on them, altering their habitats, or out-competing them in the struggle for food resources. Although biological introductions have affected environments the world over, the most destructive, effects have occurred on islands, where introduced insects, cats, pigs, rats, mongooses, and other nonnative species have caused the grave endangerment or outright extinction of literally hundreds of species during the past 500 years. One of other reason to cause species extinction is overexploitation. This word refers to the utilization of a species at a rate that is likely to cause its extreme endangerment or outright extinction. Among many examples of severe overexploitation, the case of the great whales stands out in special relief. By the middle of the 20th century, unrestricted whaling had brought many species of whales to incredibly low population sizes. In response to public pressure, in 1982 a number of nations, including the USA, agreed to an international moratorium on whaling. As a direct result, some whale species which are thought to have been on extinction's doorstep 25 years ago have made amazing comebacks, such as grey whales in the western Pacific.  Others remain at great risk. Many other species, however, continue to suffer high rates of exploitation because of the trade in animal parts. Currently, the demand for animal parts is centered in several parts of Asia where there is a strong market for traditional medicines made from items like tiger bone and rhino horn.

Exotic species _______.

Choose the letter A, B, C or D to complete the passage below

   Since China adopted its open-door (1) _____ approximately twenty-five years ago, Chinese higher education has begun once again to draw closer to the (2) _____ Western world. China's (3) _____ to send scholars and students to the United States at the end of the 1970s, after thirty years of hostility between the two countries, marked a dramatic turning (4) _____ in the nation's educational history. Today, about 50,000 Chinese students, are studying in the United States, accounting (5)_____ 10 percent of the total international students in the country.

(3).................