Have you ever heard a news reporter talk about DNA?Reporters talk about DNA found at the scene of a crime.They talk about police finding DNA "fingerprints".Police sometimes use DNA as a clue to find out who committed the crime. DNA is a substance that makes up genes.Everything alive has genes.Plants have genes.Animals have genes.You have genes. Genes are the basic units of heredity .Heredity means all the characteristics you inherit from your parents.You get your genes from your parents.You inherit half of your genes from your mother.You inherit half of your genes from your father. Genes are a kind of code.A tree's genes tell what shape its leaves will be.A cat's genes tell what color its fur will be.Your genes tell what color your eyes will be.Your genes tell what color your hair will be.Everything about you comes from the code in your genes. Genes line up on strands called chromosomes in cells.Everything alive is made up of cells.Chromosomes are in the center,or nucleus of cells. Different parts of you are made of different kinds of cells.Your muscles are made of muscle cells.Your skin is made of skin cells.The code in your genes tells your body to make different kinds of cells.The genes in each cell tell the cell how to work.They tell the cell when to make new copies of itself. An Austrian monk named Gregor Mendel first saw inherited patterns in pea plants.He experimented with pea plants in the 1860s.One of the things,or traits  Mendel studied was what makes some pea plants tall and some short.He said that the traits must come from units of heredity passed from the parent plants.These units were later called genes. In the mid-1900s,scientists discovered that genes are made of DNA.In the 1970s,scientists learned how to change DNA with genetic engineering.Scientists also learned that problems with certain genes cause diseases.Muscular dystrophy,cystic fibrosis,and hemophilia are some genetic diseases--diseases caused by problems in genes.Today,scientists are looking for ways to cure genetic diseases by... What is DNA? A) DNA is a kind of gene. B) DNA is a substance that makes up genes. C) DNA is the basic unit of heredity. D) DNA is a measure to protect crime.
B

If you put all the books you own on the street outside your house, you might expect them to disappear immediately. But one man, Hernando Guanlao in Manila, tried it and found that his collections grew. He's a lovely man in his early 60s, with one ever-lasting love--books. They're his pride and joy, because, whether he likes it or not, they seem to be taking over his house. Guanlao has set up a "library" outside his home in central Manila. Readers can take as many books as they want, for as long as they want. As Guanlao says, "The only rule is that there are no rules." You might consider it would end very quickly. But in fact, in the 12 years he's been running his library. He's found that his collection has grown rather than become smaller, as more and more people help the activity. "It seems to me that the books are speaking to me," he says with a smile, "The books are telling me they want to be read." Guanlao started his library in 2000, shortly after the death of his parents. He was looking for something to honor their memory, and that was when he hit upon the idea of promoting the reading habit passed on to him from his parents. So he put the books outside the door of his house to see if anyone wanted to borrow them. They did, and they brought the books back with others to add to the collection. The library was born. The library is not advertised, but somehow, every day, a steady stream of people find their way there. To help the poorest communities in Manila, Guanlao doesn't wait for them to find him on his "book bike". He wants to set up a "book boat", traveling around the islands of Sulu and Basilan. As we sat outside Hernando Guanlao's house in the midday sun, watching people look through his collection, he thought it was worth spending all his time. What caused Guanlao to have the idea of setting up a library? A) His good reading habit. B) The death of his parents. C) The joy of reading books. D) Nothing to do in his daily life.
B

Most people like buying things by touching them on a store shelf. Many people begin to feel some goods as theirs when they touch them. They have "mine, mine, mine" feeling as little as 30 seconds after touching an object . In a study, some people were shown a cheap coffee cup, and were allowed to hold it for 10 seconds or 30 seconds. They were then allowed to buy it in either a closed or an open place. The people knew the real price of the cup before they began to buy. If people hold the cup for a longer time, he will pay more for it. In fact, people hold the cup for 30 seconds pay more than the others. "The amazing part of this study is that people can become almost attached to something like a cup." said James Wolf,"By touching the cup and holding it in their hands, they begin to feel the cup is theirs. Once they begin to feel it as theirs, they are willing to keep it." Many businessmen use this way to sell their things. For example, car sellers send the buyers out on test drives and pet shop owners encourage people to play with the dogs in the window. When you are testing out new cars, you are going to buy it at once. But you can do better if you get ready for it. The main idea of this passage is  _  . A) more and more people don't care about the goods they want to buy B) many people are willing to pay for the goods which they would like to hold C) how do the businessmen sell their cars D) people often buy something they don't like
B

When you consider what subject to study in college, chances are that you and your parents will think about what you can make out of _ after graduation. You will likely ask the question: "Can I find a well-paid job or simply a job with a degree in this in the future?" This consideration also influences students when they come to choose between studying science or humanities   at college. People generally believe that the humanities, which include literature ,  history, cultural studies and philosophy,  do not prepare students for a specific vocation  . Science subjects, however, are considered vocational courses that produce scientists, engineers and economists  . "I've decided to take finance as my college major. My parents and I think this subject will help me get a good job or start a business," said Huachen Yueru, 17, a science student at Wuxi No. 1 High School. Even those who choose a liberal arts   education often pick the humanities subject which they think will best help them later find a job. "I'm going to study Spanish in college, which I believe will open doors to a high-paying job for me," said Liu Chao, 18, a Senior 2 student at Dalian No 20 High School. He said few of his classmates show interest in subjects like philosophy and history, which are seen as "less promising" in job markets. The popularity of liberal arts subjects among college students has also been decreasing in the United States. American scholars   and universities are concerned that in the ongoing economic crisis   liberal arts subjects will be hit hardest. As money tightens  , they worry that the humanities may become "a great luxury   that many cannot afford", according to the New York Times. What can we infer from the passage ? A) Humanities are becoming less and less popular with the students. B) Studying science subjects is sure to find a well-paid job. C) The humanities in college should be cancelled. D) The writer thinks those who choose the liberal arts education will choose their favorite subjects.

A