51、根據(jù)以下內(nèi)容回答51-70題：

　　What will man be like in the fhture——in 5000 or even 50000 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 a90，was shorter than he is todav.Now。DR average，men are about three inches taller.Five hundred years is a relatively short Deriod 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 s0，we still make use of onlv about 20%of the brain’s capacity.As time goes on，however，we shall have to use our brains more and mol.e，and eventually we shall need larger ones.This is likely to bring about a physical change to the head，in particular the forehead，will grow larger.

　　Nowadavs 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 resuh，are likely to gmw weaker.At the same time，however，our fingers will grow more sensitive because they are used a great deal in modem life.

　　But what about hair?It 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.

　　PerhaDs all this gives the impression that future man will not be a very attractive creature to look at.This may well be true.AU tIle same，in spite of all these changes，future man will still have a lot in common with US.He will still be a human bein9，with thoughts and emotions similar to our own.

　　The passage tells us about__________ .

　　A.how man’s lire will be in the future

　　B.how future man willlook like

　　C.the fact that man’s organs will function differently in the future

　　D.the fact that man is growing uglier as time passes