51、根据以下内容回答51-70题：
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


52、There is evidence that man is changing__________ ．
A．man has been growing taller over the past 500 years
B．man has got stronger eyes than he ever had
C．man’s hair is getting thinner and thinner
D．man’s limbs are getting weaker because he tends to make less use of them


53、Man’S forehead．will grow larger because__________ ．
A．he will use of only about 20％of the brain’S capacity
B．the other 80％of his brain will grow in due time．
C．he had rather narrow forehead a few hundred years ago
D．he will have to use his brain more and more as time goes on


54、Future man will probably__________ ．
A．have smaller eyes
B．see better
C．have larger eyes
D．gave to wear better glasses


55、The reason for believing that future man will be different is that he__________ ．
A．is always
B．hopes for a change
C．never stops changing
D．will live a different life

56、根据以下内容回答56-75题,
There was one thought that air pollution affected only the area immediately around large cities with factories and heavy automobile traffic．At present，we realize that although these are the．areas with the worst air pollution，the problem is literally worldWide．On several occasions over the past decade，a heavy cloud of air pollution has covered the east of the United States and brought health warnings in rural areas away from any major concentration of manufacturing and automobile tmmc．In fact，the very climate of the entire earth may be infected by air poilu-tion．Some scientists consider that the increasing concentration of carbon dioxide in the air resulting from the burning of fossil fuels(coal and oil)is creating a“greenhouse effect”——con-serving heat refleeted from the earth and raising the world’S average temperature．If this view is correct and the worid’s temperature is raised only a few degrees，much of the polar ice cap will melt and cities such as New York，Boston，Miami，and New Orleans will be in water．
Another view．1ess widely held，is that increasing particular matter in the atmosphere is blocking sunlight and lowering the earth’s temperature--a result that would be equally disas-trous．A drop of just a few degrees could create something close to a new ice age，and would make agriculture difficult or impossible in many of our top fanning areas．Today we do not know for sure that either of these conditions will happen(though one recent government report drafted bv experts in the field concluded that the greenhouse effect is#cry possible)．Perhaps，if we are lucky enough，the two tendencies will offset each other and the world’s temperature will stay about the same as it is now．
As Dointed out at the beginning of the passage，people used to think that air pollution__________ ．
A．caused widespread damage in the countryside
B．affected the entire eastern half of the United States
C．had a damaging effect on health
D．existed merely in urban and industries areas


57、As to the greenhouse effect，the author__________ ．
A．shares the same view with the scientists
B．is uncertain of its occurrence
C．rejects it as being ungrounded
D．thinks that it will destroy the world soon


58、The word“offset”in the last paragraph could be replaced by__________ ．
A．slip into
B．make up for
C．set up
D．catch up with


59、It can be concluded that
A．raising the wodd’s temperature only a few degrees w．ould not do much．harm to life on earth
B．lowering the world’s temperature merely a few degrees would lead many major farming areas to disaster
C．almost no temperature variations have occurred over the past decade
D．the world’s temperature will remain constant in the years to come


60、This passage is primarily about
A．the greenhouse effect
B．the burning of fossil fuels
C．the potential effect of air pollution
D．the likelihood of a new ice age