9. Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables. These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.
Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?
(A) Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
(B) Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
(C) Some species become extinct because of accumulated gradual changes in their local environments.
(D) In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.
(E) Species that are widely dispersed are the least likely to become extinct.
答案是A,不明白为什么A是前提
16. The imposition of quotas limiting imported steel will not help the big American steel mills. In fact, the quotas will help “mini-mills” flourish in the United States. Those small domestic mills will take more business from the big American steel mills than would have been taken by the foreign steel mills in the absence of quotas.
Which of the following, if true, would cast the most serious doubt on the claim made in the last sentence above?
(A) Quality rather than price is a major factor in determining the type of steel to be used for a particular application.
(B) Foreign steel mills have long produced grades of steel comparable in quality to the steel produced by the big American mills.
(C) American quotas on imported goods have often induced other countries to impose similar quotas on American goods.
(D) Domestic “mini-mills” consistently produce better grades of steel than do the big American mills.
(E) Domestic “mini-mills” produce low-volume, specialized types of steels that are not produced by the big American steel mills.
答案是E,Those small domestic mills will take more business from the big American steel mills than would have been taken by the foreign steel mills in the absence of quotas.为什么会发生这种情况,E为什么是削弱?
THANKS IN ADVANCE
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