题目内容
Since the early 1980s, scientists have revealed some 40 human genes involved in cancer. These genes are essential for normal growth, but can be subverted to cause a tumor.
Dr. Jorge Yunis of the University of Minnesota Medical School in Minneapolis has found that 70 percent of oncogenes, or cancer-causing genes, are located near inherited weak points on chromosomes(染色体). Varying from individual to individual, vulnerable to chemical carcinogens(致癌剂), X rays and other cancer-inducing agents.
"If a chromosome snaps apart in the immediate vicinity of an oncogene," says Yunis, "normal genetic control mechanisms could break down and the stage would be set for the formation of cancer." Younis has shown that such a sequence occurs at the beginning of numerous leukemias (白血病), lymphomas(淋巴瘤) and some tumors of the lung, colon(结肠) and breast.
Yunis and other investigators have found that petroleum-based products--notably pesticides and insecticides-damage specific sites on at least two of the 23 pairs of human chromosomes that carry genetic information. Similarly, tobacco smoke tends to attack a part of another chromosome.
From paragraph 1, we know that some 40 genes involving in cancer are ______. ()
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Let us take an obvious example. Man, even five hundred years ago, was shorter than he is today. Now, on average, men are about three inches taller. Five hundred years is a relatively short period of time, so we may assume that man will continue to grow taller. Again, in the modern world we use our brains a great deal. Even so, we still make use of only about 20% of the brain's capacity. As time goes on, however, we shall have to use our brains more and more, and eventually we shall need larger ones! This is likely to bring about a physical change too: the head, in particular the forehead, will grow larger.
Nowadays our eyes are in constant use. In fact, we use them so much that very often they become weaker and we have to wear glasses. But over very long period of time it is likely that man's eyes will grow stronger.
On the other hand, we tend to make less use of our arms and legs. These, as a result, are likely to grow weaker. At the same time, however, our fingers will grow more sensitive because they are used a great deal in modern life.
But what about hair？ This will probably disappear from the body altogether in course of time because it does not serve a useful purpose any longer. In the future, then, both sexes are likely to be bald.
Perhaps all this gives the impression that future man will not be a very attractive creature to look at! This may well be true. All the same, in spite of all these changes, future man will still have a lot in common with us. He will still be a human being, with thoughts and emotions similar to our own.
The passage mainly tells us that ______.
Many teachers believe that the responsibilities for learning lie with the student.【C1】______a long reading assignment is given, instructors expect students to be familiar with the【C2】______in the reading even if they don't discuss it in class or take an exam. The【C3】______student is considered to be【C4】______who is motivated to learn for the sake of【C5】______, not the one interested only in getting high grades. Sometimes homework is returned【C6】______brief written comments but without a grade. Even if a grade is not given, the student is【C7】______for learning the material assigned. When research is【C8】______, the professor expects the student to take it actively and to complete it with【C9】______guidance. It is the【C10】______responsibility to find books, magazines, and articles in the library. Professors do not have the time to explain【C11】______a university library works; they expect students,【C12】______graduate students, to be able to exhaust the reference【C13】______in the library. Professors will help students who need it, but【C14】______that their students should not be【C15】______dependent on them. In the United States, professors have many other duties【C16】______teaching, such as administrative or research work.【C17】______, the time that a professor can spend with a student outside of class is【C18】______If a student has problems with classroom work, the student should either【C19】______a professor during office hours【C20】______make an appointment.
【C1】
Part A
Directions: You will hear 10 short dialogues. For each dialogue, there is one question and four possible answers. Choose the correct answer ― A, B, C or D, and mark it in your test booklet. You will have 15 seconds to answer the question and you will hear each dialogue ONLY ONCE.
听力原文：W: Tom, there is a new movie in town. We must go and see it.
M: OK, but let's have breakfast first, I'm quite hungry.
W: OK, hurry up.
What does the man propose to do first？
听力原文：W: Hi, John.
M: Oh! Hi, Laura, What are you doing here？
W: Uh, I'm usually here on weekends. It's my dad's shop. So you are looking for a bike？
M: Yeah. Now that the weather is warming up, I thought I get some exercise instead of taking the bus all the time.
W: Well, you came to the right place. Do you know what you would like？
M: Well, I don't want a racer or a touring bike or anything. Mostly I'll just be using it to get me back and forth from work.
W: How far is that？
M: About four miles.
W: Are there a lot of hills on the way？
M: Some I guess. But maybe I should tell you at the front that I only got 150 dollars. Can I get anything decent for that？
W: well, you are not going to get any, thing top of the line. But we do have a few trade-ins in the back that are in good condition.
M: That sounds good.
W: And you are right. For the kind of ride you are going to be doing, the most important thing is comfort. You want to make sure it's the right height for you. Follow me and I'll show you what we've got.
Why is Laura at her dad's shop？
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