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:
By adopting a few simple techniques, parents who read to their children can considerably increase their children’s language development. It is surprising, but true. How parents talk to their children makes a big difference in the children’s language development. If a parent encourages the child to actively respond to what the parent is reading, the child’s language skills increase.
A study was done with two or three-year-old children and their parents. Half of the thirty children participants were in the experimental study; the other half acted as the control group. In the experimental group, the parents were given a two-hour training session in which they were taught to ask open-ended questions rather than yes-no questions. For example, the parent should ask, “What is the doggy doing?” rather than, “Is the doggy running away?” Experimental parents were also instructed how to expand on their children’s answer, how to suggest alternative possibilities, and how to praise correct answers.
At the beginning of the study, the children did not differ on levels of language development, but at the end of one month, the children in the experimental group were 5.5 months ahead of the control group on a test of verbal expression and vocabulary. Nine months later, the children in the experimental group still showed an advance of 6 months over the children in the control group.

What does the word “they” in the second paragraph refer to?

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.

   For centuries, time was measured by the position of the sun with the use of sundials. Noon was recognized when the sun was the highest in the sky, and cities would set their clock by this apparent solar time, even though some cities would often be on a slightly different time. Daylight Saving Time (DST), sometimes called summer time, was instituted to make better use of daylight. Thus, clocks are set forward one hour in the spring to move an hour of daylight from the morning to the evening and then set back one hour in the fall to return to normal daylight.

   Benjamin Franklin first conceived the idea of daylight saving during his tenure as an American delegate in Paris in 1984 and wrote about it extensively in his essay, "An Economical Project." It is said that Franklin awoke early one morning and was surprised to see the sunlight at such an hour. Always the economist, Franklin believed the practice of moving the time could save on the use of candlelight, as candles were expensive at the time.

   In England, builder William Willett (1857–1915) became a strong supporter for Daylight Saving Time upon noticing blinds of many houses were closed on an early sunny morning. Willet believed everyone, including himself, would appreciate longer hours of light in the evenings. In 1909, Sir Robert Pearce introduced a bill in the House of Commons to make it obligatory to adjust the clocks. A bill was drafted and introduced into Parliament several times but met with great opposition, mostly from farmers. Eventually, in 1925, it was decided that summer time should begin on the day following the third Saturday in April and close after the first Saturday in October.

   The U.S. Congress passed the Standard Time Act of 1918 to establish standard time and preserve and set Daylight Saving Time across the continent. This act also devised five time zones throughout the United States: Eastern, Central, Mountain, Pacific, and Alaska. The first time zone was set on "the mean astronomical time of the seventy-fifth degree of longitude west from Greenwich" (England). In 1919, this act was repealed.

   President Roosevelt established year-round Daylight Saving Time (also called War Time) from 1942–1945. However, after this period, each state adopted its own DST, which proved to be disconcerting to television and radio broadcasting and transportation. In 1966, President Lyndon Johnson created the Department of Transportation and signed the Uniform Time Act. As a result, the Department of Transportation was given the responsibility for the time laws. During the oil embargo and energy crisis of the 1970s, President Richard Nixon extended DST through the Daylight Saving Time Energy Act of 1973 to conserve energy further. This law was modified in 1986, and Daylight Saving Time was reset to begin on the first Sunday in April (to spring ahead) and end on the last Sunday in October (to fall back).

The word “it” in paragraph 2 refers to

Choose the correct answer  A, B, C or D to the blank space in the following passage:

"If you want to (1)…… your best in an exam, you should be relaxed and so one of the best things to do is to take regular (2)….. even if they are only for a few minutes. During revision time, you (3)….. take some time off to go for a walk or play your (4)…..  sport. It is a mistake to (5)….. up all physical activity. Exercise can (6)…. you to relax. You should (7)….  at least twenty minutes doing something different every day. Parents don’t like it when their teenage children spend (8)…..  on the phone, but, in fact, (9)…. to a friend is very good for you; parents think that children are (10)…. time and money; but research says talking to friends gives you a chance to relax, and this will make the time you spend studying more effective."

4.you ….. take some time off to go for a walk or play your (4)…..  sport. 

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.
When John Mills was going to fly in an airplane for the first time, he was frightened. He did not like the idea of being thousands of feet up in the air. "I also didn't like the fact that I wouldn't  be in control," says John.
"I'm a terrible passenger in the car. When somebody else is driving, I tell them what to so. It drives everybody crazy."
However John couldn't avoid flying any longer. It was the only way he could visit his grandchildren in Canada.
"I had made up my mind that I was going to do it, I couldn't let my son, his wife and their three children travel all the way here to visit me. It would be so expensive for them and I know Tom's business isn't doing so well at the moment - it would also be tiring for the children - it's a nine-hour flight!" he says.
To get ready for the flight John did lots of reading about airplanes. When he booked his seat, he was told that he would be flying on a Boeing 747, which is better known as a jumbo jet. "I  needed to know as much as possible before getting in that plane. I suppose it was a way of making myself feel better. The Boeing 747 is the largest passenger aircraft in the world at the moment.
The first one flew on February 9th 1969 in the USA. It can carry up to 524 passengers and 3.400 pieces of luggage. The fuel for airplanes is kept in the wings and the 747's wings are so big that they can carry enough fuel for an average car to be able to travel 16,000 kilometers a year for 70 years. Isn't that unbelievable? Even though I had discovered all this very interesting information about the jumbo, when I saw it for the first time, just before I was going to travel to Canada, I still couldn't believe that something so enormous was going to get up in the air and fly. I was even more impressed when I saw how big it was inside with hundreds of people!"
The biggest surprise of all for John was the flight itself. "The take-off itself was much smoother than I expected although I was still quite scared until we were in the air. In the end, I managed to relax, enjoy the food and watch one of the movies and the view from the window was spectacular. I even managed to sleep for a while!
"Of course," continues John, "the best reward of all was when I arrived in Canada and saw my son and his family, particularly my beautiful grandchildren. Suddenly, I felt so silly about all the years when I couldn't even think of getting on a plane. I had let my fear of living stop me from seeing the people I love most in the world. I can visit my son and family as often as I like now!" Question 24: Why did John Mills fly in an airplane?

Why did John read about airplane?

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141...................

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:
The concept of obtaining fresh water from iceberg that is towed to populated areas and arid regions of the world was once treated as a joke more appropriate to cartoons than real life. But now it is being considered quite seriously by many nations, especially since scientists have warned that the human race will outgrow its fresh water supply faster than it runs out of food. Glaciers are a possible source of fresh water that has been overlooked until recently. (A)
Three-quarters of the Earth's fresh water supply is still tied up in glacial ice, a reservoir of untapped fresh water so immense that it could sustain all the rivers of the world for 1,000 years. Floating on the oceans every year are 7,659 trillion metric tons of ice encased in 10,000 icebergs that break away from the polar ice caps, more than ninety percent of them from Antarctica. (B)
Huge glaciers that stretch over the shallow continental shelf give birth to icebergs throughout the year. Icebergs are not like sea ice, which is formed when the sea itself freezes; rather, they are formed entirely on land, breaking off when glaciers spread over the sea. As they drift away from the polar region, icebergs sometimes move mysteriously in a direction opposite to the wind, pulled by subsurface  currents. Because they melt more slowly than smaller pieces of ice, icebergs have been known to drift as far north as 35 degrees south of the equator in the Atlantic Ocean. (C)
The difficulty arises in other technical matters, such as the prevention of rapid melting in warmer climates and the funneling of fresh water to shore in great volume. But even if the icebergs lost half of their volume in towing, the water they could provide would be far cheaper than that produced by desalination, or removing salt from water. (D)

The word “it” in the first paragraph refers to     .

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:
Facebook users spend an average of more than 15 hours a month on the social networking site. While there are plenty who caution against such intensive use — and there are a number of studies detailing the harm Facebook could potentially cause — there also are lots of reports extolling the site's virtues. As the social media giant prepares for its upcoming initial public offering, here are some ways Facebook just might be good for you.
Spending time on Facebook can help people relax, slow down their heart rate and decrease stress levels, according to researchers from the Massachusetts Institute of Technology and the University of Milan. In a study published earlier this year, researchers studied 30 students and  found that a natural high was sparked when they were on  the  social media network that led  to  the relaxed heart rates and lower levels of stress and tension. In the study, the students were monitored in three situations: looking at panoramic landscapes, performing complicated mathematical equations and using Facebook. While the first situation was the most relaxing to students and the math problems were the most stressful, the time on Facebook uncovered high levels of attractiveness and arousal. The findings support the researchers' hypothesis that Facebook's success, as well as that of other social media networks, correlates to the specific positive mental and physical state users experience.
While many may argue that social media networks only distract employees, research shows  the opposite may be true. Research from Keas.com found that a 10-minute Facebook break makes employees happier, healthier and more productive. The study examined workers in three groups: one that was allowed no  breaks, one that was allowed to do  anything but use the Internet and one  that was allowed 10 minutes to use the Internet and Facebook. The Facebook group was found to be 16 percent more productive than the group that was not allowed to use the Internet and nearly 40 percent more productive than the group that was allowed no breaks. "Short and unobtrusive breaks, such as a quick surf on the Internet, enables the mind to rest itself, leading to a higher net total concentration for a day's work, and as a result, increased productivity," said Brent Coker of the department of management and marketing at the University of Melbourne in Australia.
Facebook is also in the business of matchmaking. Research shows that nearly 60 percent of singles will friend someone new on Facebook after meeting them in  person. If  they like what they see, 25 percent are likely to contact their new love interest via Facebook. Once the courting is over, nearly 40 percent of those social networking adults will update their relationship status on Facebook, with just 24 percent telling their friends first. Facebook use between couples will continue through the dating process, the research shows. Throughout the day, 79 percent of  couples  said they send partners Facebook messages or chat on the social network. In addition, more than 60 percent would post romantic messages on their significant other's Facebook wall. When the relationship ends, more than half of those surveyed immediately update their status to single, which automatically sends out a notification to their friend list to start the dating cycle over again.

The word "sparked" in the second paragraph probably means    _.

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:
Translators and interpreters for tech jobs of the future are expected to be one of the fastest growing occupations in the nation, according to a just released survey by Vietnamworks. Almost all positions for programmers, application developers, database and network administrators, engineers, designers, architects, scientists, technicians, and tech support will require bilingual or multilingual fluency. In just the last two years the demand for tech professionals with foreign language skills has increased more than two and one-half fold, said the survey, and the uptick shows no signs of abating anytime soon. Roughly 400,000 jobs are expected to open for interpreters (who focus on spoken language) and translators (who focus on written language) in the tech segment, between 2017 and 2020, says Tran Anh Tuan. Tuan, who works for the Centre for Forecasting Manpower Needs and Labour Market Information in Ho Chi Minh City doesn't include other industries in his prediction,
which are also recruiting ferociously for more people with these same language skills.
While that claim might seem a bit overblown (and amounts to little more than a guess by Tuan), it is clear that innovative technologies like robotics, 3D printing, drones, artificial intelligence   and virtual reality will create major upheavals in all sorts of labor markets, not just technology over     the next few years. In the last month alone, most every job posted on employment websites throughout Vietnam included the word bilingual. Far higher salaries go to people who work in high    tech positions and can speak a foreign language such as English in addition to Vietnamese, says Tran Quang Anh from the Posts and Telecommunications Institute of Technology.
Unfortunately, the surveys show that most graduating Vietnamese students are unable to do more than understand a few basic phrases of foreign languages, and practically none of them  can speak any foreign language coherently, The good paying jobs with high salaries and benefits are only available to translators and interpreters who specialize in high tech jobs, says Anh. But it's    not just English— graduates are needed with fluency in middle eastern languages like  Arabic, Farsi and Pashto (Afghani) as well as German, Japanese and Korean to name just a few. Spanish is  also in high demand in Vietnam, primarily because it is the second most common language in the US after English.
A recent tech expo in Hanoi sponsored by Vietnamworks and the Navigos Group attracted nearly 4,000 young tech graduates and recruiters from 14 leading companies looking to fill job  vacancies with skilled bilingual workers. The job applicants were young and industrious, said the recruiters. However, missing were candidates with the requisite language skills and most lacked  basic 'soft skills' such as written and verbal communication abilities to effectively communicate  even in their native Vietnamese language.
Notably, the recruiters said they considered language abilities and soft skills just as, if not more important, than academic ability. Yet virtually all the prospective academically qualified employees lacked even the most basic of interpersonal communication abilities.

Which of the following most accurately reflects the attitude of the author towards improving foreign language skills?

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:
Because the low latitudes of the Earth, the areas near the equator, receive more heat than the latitudes near the poles, and because the nature of heat is to expand and move, heat is transported from the tropics to the middle and high latitudes. Some of this heat is moved by winds and some by ocean currents, and some gets stored in the atmosphere in the form of latent heat. The term “latent heat” refers to the energy that has to be used to convert liquid water to water vapor. We know that if we warm a pan of water on a stove, it will evaporate, or turn into vapor, faster than if it is allowed to sit at room temperature. We also know that if we hang wet clothes outside in the summertime, they will dry faster than in winter, when the temperature is lower. The energy used in both cases to change liquid water to water vapor is supplied by heat - supplied by the stove in the first case and by the Sun in the latter case. This energy is not lost. It is stored as vapor in the atmosphere as latent heat. Eventually, the water stored as vapor in the atmosphere will condense to liquid again, and the energy will be released to the atmosphere.
In the atmosphere, a large portion of the Sun’s incoming energy is used to evaporate water, primarily in the tropical oceans. Scientists have tried to quantify this proportion of the Sun’s energy. By analyzing temperature, water vapor, and wind data around the globe, they have estimated the quantity to be about 90 watts per square meter, or nearly 30 percent of the Sun’s energy. Once this latent heat is stored within the atmosphere, it can be transported, primarily to higher latitudes, by prevailing, large - scale winds. Or it can be transported vertically to higher levels in the atmosphere, where it forms clouds and subsequent storms, which then release the energy back to the atmosphere.

The word “marked” in the first paragraph is closest in meaning to     .

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:
In ancient Greece, athletic festivals were very important and had strong religious associations. The Olympic athletic festival, held every four years in honour of Zeus, eventually lost its local character, became first a national event, and then, after the rules against foreign competitors had been abolished, international. No one knows exactly how far back the Olympic Games go, but some official records date from 776 B.C.
The Games took place in August on the plain by Mount Olympus. Many thousands of spectators gathered from all parts of Greece, but no married woman was admitted even as a spectator. Slaves, women and dishonoured people were not allowed to compete. Records show that the evening of the third day was devoted to sacrificial offerings to the heroes of the day, and the fourth day, that of the full moon, was set aside as a holy day. On the sixth and last day all the victors were crowned with holy garlands of wild olive from a sacred wood. So great was the honour that the winner of the foot race gave his name to the year of his victory. How their results compared with modern standards, we unfortunately had no means of telling.
After an uninterrupted history of almost 1,200 years, the Games were abolished in A. D. 394 because of their pagan origin. It was a great many years before there was another such international athletic gathering. The Greek institution was brought back into existence in 1896 and the first small meeting took place in Athens. After the 1908 London Olympics, success was re-established and nations sent their best representatives.
Today, the Games are held in different countries in turn. The host country provides vast facilities, including a stadium, swimming pools and living accommodation, but competing countries pay their own athletes' expenses. Athletic contests are still the main feature, but now many more sports are represented, women compete, the ancient pentathlon, for example, has been modified into a more comprehensive test, and the marathonraces, initiated in 1896, are now a celebrated event.
The Olympics start with the arrival in the stadium of a torch, lighted on Mount Olympus by the sun's rays. It is carried by a succession of runners to the stadium. The torch symbolizes the continuation of the ancient Greek athletic ideals, and it burns throughout the Games until the closing ceremony.

During the Games, on the evening before the moon was full,     .

Choose the best answer:
I think in the future many people will prefer ____________ by using social media.
 

Five years ago, Brian Trang signed a  five-year lease to open his restaurant, Trang's Bistro, at 30 Luray Place. Mr. Trang admits that the first two years of operation were quite---131---. "We offer spicy food from Vietnam's central region," he explains. "We didn't do well at first ---132--- the cuisine is based on unfamiliar herbs and hot flavors. It took a while to catch on with customers." But Mr. Trang was confident the food would gain in popularity, and he was correct.---133---. Mr. Trang has just signed another five-year lease, and he is planning ---134--- the space next year.

134...................

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
Parents and teachers are always making (1)......... between the time when they were children and the present generation . They say everything was better than it is today, especially in education. (2)........ , they say they used to work much harder in school, and that nowadays, we aren’t very interested. I disagree, because we spend hours every day doing homework after our lessons or (3)........... for exammination. I wonder (4)..........our parents really had to study so much after school every day. In my opinion, it is no exaggeration to say we have forgotten how to play. I think one reason why kids (5)........... in class is because they need to get rid of stress.
(5).............................

Read the passage and choose the best option A, B, C, D to complete it.

Full Moon festival, also known as Mid-Autumn Festival or ‘Tet Trung Thu’ in Vietnamese is held (1) _________ the 14th and 15th of the August lunar month. This is an (2) _________ harvest festival celebrated not only in Vietnam (3) ________ in other wet rice countries in Asia such as China, Taiwan, Hongkong, Japan, and Korea. The Full Moon festival offers leisure time for family members to come back home, organize and participate in a wide range of activities including children carrying paper lanterns, lion dances, ….

In fact, there aren’t (4) _______ important customs you must follow but it is good to find wonderful places to visit during this period. Mid-Autumn festival is best enjoyed in Hoi An by strolling down and admiring (5) ______ paper lanterns floating the Thu Bong Riverside. If you base in Hanoi, it is (6) _______ recommended to go to Thang Long Royal Citadel, My Dinh National Stadium, and Hoan Kiem Lake to enjoy a festive atmosphere of fun, safety, and peace.
2.  This is an (2) _________ harvest festival celebrated not only in Vietnam (3) ________ in other wet rice countries in Asia such as China, Taiwan, Hongkong, Japan, and Korea.

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.
Christina and James met in college and have been dating for more than five years. For the  past two years, they have been living together in a  condo  they  purchased jointly. While Christina and James were confident in their decision to enter into a commitment like a  20-year mortgage,  they are unsure if they want to enter into marriage. The couple had many discussions about marriage and decided that it just did not seem necessary. Wasn't it only a piece of  paper? And  didn't half of all marriages end in divorce?
Neither Christina nor James had seen much success with marriage while growing up. Christina was raised by a single mother. Her parents never married, and her father has had little contact with the family since she was a toddler, Christina and her mother lived with her maternal grandmother, who often served as a surrogate parent. James grew up in  a  two-parent household  until age seven, when his parents divorced. He lived with his mother for a  few years, and then    later with his mother and her boyfriend until he left for college. James remained close with his  father who remarried and had a baby with his new wife.
Recently, Christina and James have been thinking about having children and the subject of marriage has resurfaced. Christina likes the idea of her children growing up in a traditional  family; while James is concerned about possible marital problems down the road and negative consequences for the children should that occur. When they shared these concerns with their parents, James's mom was adamant that the couple should get married. Despite having been divorced and having a live-in boyfriend of 15  years, she believes that children are better off when  their parents are married. Christina's mom believes that the couple should do whatever they want but adds that it would "be nice" if they wed. Christina and James's friends told them, married or not married; they would still be a family.

What is the advice of the couple's parents?

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:
Around 365 B.C. in ancient Greece, the great teacher Plato told a story about a place called Atlantis. Plato described Atlantis as a continent in the Atlantic Ocean. He said it had been the home of a powerful people who were destroyed when the continent was swallowed by the sea.
Ever since Plato’s time, people have wondered if the story about Atlantis was really true. Was there ever such a place as Atlantis? During the Middle Ages, many people believed in the legend of Atlantis. Some men even made voyages to find the “lost continent”. Later, most people believed Atlantis to be just a myth. Scientists could find no evidence to show that such a place had ever existed.
Ideas change in time, however, for now some scientists think that Atlantis might have been a real place. A Greek professor has offered a new theory. He says that Atlantis was not a continent in the Atlantic Ocean but an island called Thera in the Aegean Sea. The professor says that 3,500 years ago much of Thera collapsed into the sea when a volcano erupted. He thinks that before the explosion Thera had been the home of a people called Minoans. The Minoans were sea traders who ruled the Aegean Sea from 2,000
B.C. to 1,250 B.C.
Scientist who have come to investigate Thera have found an ancient city buried beneath volcanic ash and stone. It appears that the people who lived in the city had an advanced civilization. They were probably Minoans.
Is Thera the “lost continent” of Atlantis? No one may ever know for certain. Atlantis may remain a riddle without an answer.

Who were the ancient Minoans?

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions.
                      My first home
When my parents married, they rented a small house and they didn’t have a lot of money for furniture. The kitchen had a sink for washing up and a cooker, but that was all. They (6)............. a old table and a chair from the market. They borrowed a sofa (7)....... _was also old but they covered it with modern materials so it was bright and cheerful.
Outside, there was a small garden behind the house, but in front of it there was only the road. (8).........., the road wasn’t busy, so I could cross it to reach the park on the opposite side. We   lived there (9)..........I was ten and we were very happy. We had to move house because it was too small when my twin sisters were born. We all (10).......... sad when we left.

(8)..........................

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
We can (29)............ other people in many different ways. We can talk and write, and we can send messages with our hands and faces. There is also the phone (including the mobile!), the fax, and e-mail. Television, film, painting, and photography can also communicate ideas.
Animals have ways of exchanging information, too. Bees dance and tell other bees where (30)................. food. Elephants make sounds that humans can’t hear. Whales sing songs. Monkeys use their faces to show anger and love. But this is nothing (31)............._ to what people can do. We have language - about 6,000 languages, in fact. We can write poetry, tell jokes, make promises, explain, persuade, tell the truth, or tell lies. And we have a sense of past and future, not just present.
Radio, film, and television (32)......... a huge influence on society in the last hundred years. And now we have the Internet, which is infinite. But what is this doing to this? We can give and get a lot of information very quickly. But there is (33)........... information that it is difficult to know what is important and what isn’t. Modem media is changing our world every minute of every day.
(31)................................

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

"The Internet was born (1) _________scientists attempted to connect the American Defence Network to other satellite networks in (2) _________to exchange information. Soon, scientific and educational institutions as well as research departments became interested (3) _________ linking up, and, before long, the Internet had expanded into an international information and communication network.

The Internet now (4) _________ all the countries in the world. You can be connected to the Internet directly through your own computer or you can hook up to (5) _________ access system which allows you to use some of the Internet’s services."

1. The Internet was born (1) _________scientists attempted to connect the American Defence Network

Choose the best answer:
Robots in factories will be able to do everything the workers do, __________ robots will make them jobless.

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:
The technology of the North American colonies did not differ strikingly from that of Europe, but in one respect, the colonists enjoyed a great advantage. Especially by comparison with Britain, Americans had a wonderfully plentiful supply of wood.
The first colonists did not, as many people imagine, find an entire continent covered by a climax forest. Even along the Atlantic seaboard, the forest was broken at many points. Nevertheless, all sorts of fine trees abounded, and through the early colonial period, those who pushed westward encountered new forests. By the end of the colonial era, the price of wood had risen slightly in eastern cities, but wood was still extremely abundant.
The availability of wood brought advantages that have seldom been appreciated. Wood was a foundation of the economy. Houses and all manner of buildings were made of wood to a degree unknown in Britain. Secondly, wood was used as fuel for heating and cooking. Thirdly, it was used as the source of important industrial compounds, such as potash, an industrial alkali; charcoal, a component of gunpowder; and tannic acid, used for tanning leather.
The supply of wood conferred advantages but had some negative aspects as well. Iron at that time was produced by heating iron ore with charcoal. Because Britain was so stripped of trees, she was unable to exploit her rich iron mines. But the American colonies had both iron ore and wood; iron production was encouraged and became successful. However, when Britain developed coke smelting, the Colonies did not follow suit because they had plenty of wood and besides, charcoal iron was stronger than coke iron. Coke smelting led to technologic innovations and was linked to the emergence of the Industrial Revolution. In the early nineteenth century, the former colonies lagged behind Britain in industrial development because their supply of wood led them to cling to charcoal iron.

Which of the following is NOT mentioned as a source of industrial compounds?