题目

在光滑水平面上有两个质量均为2 kg的质点，质点a在水平恒力Fa=6 N作用下由静止开始运动6 s，质点b在水平恒力Fb=6 N作用下由静止开始运动6 m，比较这两质点所经历的过程，可以得到的正确结论是(    )A.质点a的位移比质点b的位移小B.质点a的末速度比质点b的末速度小C.力Fa做的功比力Fb做的功小D.力Fa的冲量比力Fb的冲量大What will man be like in the future — in 5,000 or even 50,000 years from now? We can only make guesses, of course, but we can be sure that he will be different from what he is today, for man is slowly changing all the time. 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 relatively a short period of time, so we may suppose 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(容量). As time goes on, however, we shall have to use our brains more and more, and finally we shall need our brains more and more, and finally we shall need larger ones! This is likely to bring 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 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 motions similar to our own. 1.The passage mainly tells us that __________. A．Man’s life will be different in the future B．Future man will look quite different from us C．Man is growing taller and uglier as time passes D．Man’s organs’ functions will change 2.What serves as the evidence that man is changing? A．Man has got stronger eyes now than he ever had. B．Man’s hair is getting thinner and thinner. C．Man’s arms and legs have become lighter and weaker. D．Man has been growing taller over the past 500 years. 3.The change in man’s size of the forehead is probably because __________. A．he makes use of only 20% of the brain’s capacity B．his brain has grown larger over the past centuries C．he will use his brain more and more as time goes on D．the other 80% of his brain will grow in due time 4.Which of the following is TRUE about a human being in the future? A．He is hairless because hair is no longer useful. B．He has smaller eyes and wears better glasses. C．His fingers grow weaker because he doesn’t have to make use of them. D．He thinks and feels in a different way. 5.It is implied that __________. A．human beings will become less attractive in the future B．body organs will become poorer if they are not used often C．human beings hope for a change in the future life D．future life is always predictable