57. 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.
我对于题干不是很了解。
想确定一下 random pattern of extinctions 和a surprisingly definite pattern有什么不同,是不是说一个是随机模式,一个是确定的模式?
A只是解释了为什么会数量多,可是没有解释上面的矛盾呀?!难道我理解题目有误?!
盼解答,谢谢!:) |