According to the passage, biological agents mainly consist of ____________.

According to the writer, why is the choice of your second job important?

“Where is the university?” is a question many visitors to Cambridge ask, but no one can give them a clear answer, for there is no wall to be found around the university. The university is the city. You can find the classroom buildings, libraries, museums and offices of the university all over the city. And most of its members are the students and teachers or professors of the thirty-one colleges. Cambridge is already a developing town long before the first students and teachers arrived 800 years ago. It grew up by the river Granta, as the Cam was once called. A bridge was built over the river as early as 875. In the fourteenth and fifteenth centuries, more and more land was used for college buildings. The town grew faster in the nineteenth century after the opening of the railway in 1845. Cambridge became a city in 1951 and now it has the population of over 100000. Many young students want to study at Cambridge. Thousands of people from all over the world come to visit the university town. It has become a famous place all around the world. 

Why did people name Cambridge the “city of Cambridge”?

According to the passage, what is noise?

Who talks more - men or women? Most people believe that women talk more. However, linguist Deborah Tannen, who has the studied the communication style of men and women, says that this is a stereotype. According to Tannen, women are more verbal - talk more - in private situations, where they use conversation as the “glue’ to hold relationships together. But, she says, men talk more in public situations, where they use conversation to exchange information and gain status. Tannen points out that we can see these difference even in children. Little girls often play with one ‘best friend’ and their play includes a lot of conversation. Little boys often play games in groups, their play usually involves more doing than talking. In school, girls are often better at verbal skills, while boys are often better at mathematics. A recent study at Emory University helps to shed light on the roots of this difference. Researchers studied conversation between children aged 3-6 and their parents. They found evidence that parents talk very differently to their sons than they do to their daughters. The startling conclusion was that parents use more language with their girls. Specifically, when parents talk with their daughters, they use more descriptive language and more details. There is also far more talk about emotions, especially with daughters than with sons. 

Which sentence best expresses the main idea of the first paragraph?

What can be inferred about the defense mechanisms of the sea cucumber?

Scientists do not yet thoroughly understand just how the body of an individual becomes sensitive to a substance that is harmless or even wholesome for the average person. Milk, wheat, and egg, for example, rank among the most healthful and widely used foods. Yet these foods can cause persons sensitive to them to suffer greatly. At first, the body of the individual is not harmed by coming into contact with the substance. After a varying interval of time, usually longer than a few weeks, the body becomes sensitive to it, and an allergy has begun to develop. Sometimes it's hard to figure out if you have a food allergy, since it can show up so many different ways. Your symptoms could be caused by many other problems. You may have rashes, hives, joint pains mimicking arthritis, headaches, irritability, or depression. The most common food allergies are to milk, eggs, seafood, wheat, nuts, seeds, chocolate, oranges, and tomatoes. Many of these allergies will not develop if these foods are not fed to an infant until her or his intestines mature at around seven months. Breast milk also tends to be protective. Migraines can be set off by foods containing tyramine, phenathylamine, monosodium glutamate, or sodium nitrate. Common foods which contain these are chocolate, aged cheeses, sour cream, red wine, pickled herring, chicken livers, avocados, ripe bananas, cured meats, many Oriental and prepared foods (read the labels!). Some people have been successful in treating their migraines with supplements of B-vitamins, particularly B6 and niacin. Children who are hyperactive may benefit from eliminating food additives, especially colorings, and foods high in salicylates from their diets. 

The topic of this passage is______________.

What is the most likely subject of the paragraph following this passage?

If you visit an American friend at home in the evening, you may find that your friend wears .............

In the United States, it is important to be on time, or punctual, for an appointment, a class, a meeting, etc... This may not be true in some other countries, however. An American professor discovered this difference while teaching a class in a Brazilian university. The twohour class was scheduled to begin at 10 a.m, and end at 12 a.m. On the first day, when the professor arrived on time, no one was in the classroom. Many students came after 11 a.m. Although all of the students greeted the professor as they arrived, few apologised for their lateness. Were these students being rude? He decided to study the students’ behavior. In American university, students are expected to arrive at the appointed hour. On the other hand, in Brazil, neither the teacher nor the students always arrive at the appointed hour. Classes not only begin at the scheduled time in the United States, but they also end at the scheduled time. In the Brazilian class, only a few students left the class at noon, many remained past 12:30 to discuss the class and ask more questions. While arriving late may not be important in Brazil, neither is staying late. The explanation for these differences is complicated. People from Brazilian and North American cultures have different feelings about lateness. In Brazil, the students believe that a person who usually arrives late is probably more successful than a person who is always on time. In fact, Brazilians expect a person with status or prestige to arrive late, while in the United States, lateness is usually considered to be disrespectful and unacceptable. Consequently, if a Brazilian is late for an appointment with a North America, the American may misinterpret the reason for the lateness and become angry. As a result for his study, the professor learned that the Brazilian students were not being disrespectful to him. Instead, they were simply behaving the appropriate way for a Brazilian student in Brazil. Eventually, the professor was able to adapt his own behavior to feel comfortable in the new culture. 

What is the main idea of this passage?

Under certain circumstances, the human body must cope with gases at greater-than-normal atmospheric pressure. For example, gas pressures increase rapidly during a drive made with scuba gear because the breathing equipment allows divers to stay underwater longer and dive deeper. The pressure exerted on the human body increases by 1 atmosphere for every 10 meters of depth in seawater, so that at 39 meters in seawater a diver is exposed to pressure of about 4 atmospheres. The pressure of the gases being breathed must equal the external pressure applied to the body, otherwise breathing is very difficult. Therefore all of the gases in the air breathed by a scuba diver at 40 meter are present at five times their usual pressure. Nitrogen, which composes 80 percent of the air we breathe, usually causes a balmy feeling of well-being at this pressure. At a depth of 5 atmospheres, nitrogen causes symptoms resembling alcohol intoxication, known as nitrogen narcosis. Nitrogen narcosis apparently results from a direct effect on the brain of the large amounts of nitrogen dissolved in the blood. Deep dives are less dangerous if helium is substituted for nitrogen, because under these pressures helium does not exert a similar narcotic effect. As a scuba diver descends, the pressure of nitrogen on the lungs increases. Nitrogen then diffuses from the lungs to the blood, and from the blood to body tissues. Nitrogen then diffuses from the lungs to the blood, and from the blood to body tissues The reverse occurs when the diver surfaces, the nitrogen pressure in the lungs falls and the nitrogen diffuses from the tissues into the blood, and from the blood into the lungs. If the return to the surface is too rapid, nitrogen in the tissues and blood cannot diffuse out rapidly enough and nitrogen bubbles are formed. They can cause severe pains, particularly around the joints. Another complication may result if the breath is held during ascent. During ascent from a depth of 10 meters, the volume of air in the lungs will double because the air pressure at the surface is only half of what it was at 10 meters. This change in volume may cause the lungs to distend and even rupture. This condition is called air embolism. To avoid this event, a diver must ascend slowly, never at a rate exceeding the rise of the exhaled air bubbles, and must exhale during ascent. 

The word “exert” in bold in paragraph 1 is closest in meaning to ...............