A、Thirty percent. B、Twenty percent. C、Fifty percent. D、Ten percent. B

What will man be like in the future--in 5,000 or even 50,000 years from now.’? We can only make a guess,  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 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 a 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 modem life.