Back in old times, people had little knowledge about the universe and nature. Things we now consider to be common sense were mysteries to our ancestors. Over the years, major breakthroughs have been made in science and many phenomena have been explained. But still, there are always questions we can't yet answer, and The Guardian has listed some of them. 1. What makes us human? Just looking at your DNA won't tell you - human DNA is 99 percent _ to that of the chimpanzee and, believe it or not, 50 percent identical to a banana's! A lot of the things we once thought were unique about us - language and tool use, recognizing ourselves in the mirror and so on - have since been seen in other animals. Perhaps it's our culture that makes the difference or maybe our ability to use fire. It's also possible that our capacity   for co-operation and our trading skills are what make us unique. 2. Why do we dream? Given the fact that we spend around a third of our lives sleeping, shouldn't we know everything about it? Unfortunately, scientists are still searching for a complete explanation of what happens when we sleep and why we dream. Austrian psychologist Sigmund Freud believed dreams were the expressions of wishes that we can't fulfill in our real lives. Others have wondered whether dreams are just random "noise" coming from a sleeping brain. 3. Could we someday live forever? Apart from accidents, most people die because of diseases that can be treated and aging. And since many diseases, such as diabetes  and cancer, are diseases of aging, treating aging itself could be the key to extending our lives. Our knowledge of what causes us to age - and what allows some animals to live longer than others - is expanding rapidly. And though we haven't quite worked out all the details, we've worked out some pieces of the puzzles such as DNA damage and metabolism  , which are all leading to the invention of drugs that can slow down the aging process. If we're lucky enough to lengthen our lives, we might even get to see the day when... Which of the following statements is TRUE according to the passage? A) What were mysteries to our ancestors are considered to be common sense now. B) Now we know much more about dreams than our ancestors did in the past. C) With the invention of new drugs people can possibly live even longer. D) If all the diseases can be treated people can theoretically live forever.
C
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Digital wallets have been called the future of real-world payment technology. With major players like Alipay, WecChat and Apple Pay becoming popular, it seems to be a safe bet that a change in consumer payment technology is coming soon. A recent study by Citi Retail Services found that a growing number of people are embracing digital wallets, due in large part to their convenience and ease of use , "There's no question 2016 will be an important year as digital wallets gain more acceptance.", Leslie MeNamara, managing director of partner management, Citi Retail Services, noted. Last month, CNN reporter Will Ripley experience a day in Beijing without his wallet. "In China's largest cities, you can definitely survive without carrying a pocket full of cash and credit cards- as long as you've got your smartphone," he wrote. "A huge number of businesses in Beijing accept mobile payments." He paid for breakfast by scanning a QR code on the window of a hole-in-the -wall restaurant. All he had to do was enter a password and the transaction  was completed. Then he also used his phone to pay for movies tickets, buy takeout food, order goods for delivery. In fact, he was not the only one to enjoy this convenience. His assistant Shen Lu also paid her household water bill with her mobile phone. In seconds, she was able to transfer funds( ) from one of several linked accounts. Unlike the situations in the US and other countries, "China doesn't have a really money-making credit card system". Gu Yu, co-founder of the new payment app Mileslife, told CNN. "So Chinese people just skipped credit cards and wet straight to mobile payments." Gu also pointed out the advantages of mobile payments. "No coins or bills that can be lost or stolen, electronic receipts, the ease of keeping track of spending and of course, no wallet taking up space." he said What is the article mainly about? A) How to survive with no cash or credit cards at hand in China. B) Differences between mobile payments and traditional cash payments. C) The increasing popularity of digital wallets in China and the reasons behind it. D) Differences in payments between America and China.
C
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Today, people all over the world are moving out of small villages in the country to go and live in big, noisy cities. They are moving from the peaceful hills, mountains, fields, rivers and streams of the countryside to the busy world of streets, buildings, traffic and crowds. This movement from rural  areas to urban areas has been going on for over two hundred years. In many countries, the main reason people come to live in towns and cities is work. After one or two large factories have been built in or near a town, people come to find work, and soon an industrial area begins to grow. There is usually _ nearby, too. The families of these workers need schools, hospitals and shops, so many people come to live in the area to provide these services and a city grows. In every major city in the world, there is a business district where the big companies have their main offices. In the United States, this area is usually in the city center downtown. It is here that you can see many huge skyscrapers and office blocks. The people who work here often travel a long way to work each day. Many of them live in the suburbs of the city, far away from the industrial area and the city center. Some suburbs are very pleasant, with nice houses and big gardens. There are usually parks for children to play in and large department stores where you can buy all you need. But what is the future of the big cities? Will they continue to get bigger and bigger? Perhaps not. Some major cities have actually become smaller in the last ten years, and it is quite possible that one day we will see people moving out of the major cities and back into smaller towns and villages. Which of the following statement is NOT true about the business district? A) Big companies usually have their main offices in the business district. B) People usually work and live in the business district. C) A business district usually lies in the city center downtown. D) Nearly every major city has its own business district.

B
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