Questions 33-34

Conservationist: The population of a certain wildflower is so small that the species is headed for extinction. However, this wildflower can cross-pollinate with a closely related domesticated daisy, producing viable seeds. Such cross-pollination could result in a significant population of wildflower-daisy hybrids. The daisy should therefore be introduced into the wildflower’s range, since although the hybrid would differ markedly from the wildflower, hybridization is the only means of preventing total loss of the wildflower in its range.

34. Which one of the following is an assumption on which the conservationist’s reasoning depends?

A. The wildflower currently reproduces only by forming seeds.

B. The domesticated daisy was bred from wild plants that once grew in the wildflower’s range.

C. Increasing the population of the wildflower will also expand its range.

D. Wildflower-daisy hybrids will be able to reproduce.

E. The domesticated daisy will cross-pollinate with any daisy like plant.

思路：not+weaken。根据原命题成立则逆否命题成立的原理，把选项取非后，若能对文章产生削弱作用的，则为答案。

A. 与结论无关。另外也可以根据极端词only来进行排除。

B. 就算daisy不是in wildflower's range，wildflower-daisy hybrids也是in wildflower's range。

C. 无关。

D. 把选项取非，变成：wildflower-daisy hybrids不能再繁殖。这样的话，总有一天，随着wildflower的消失，wildflower-daisy hybrids也会消失的，这样就不能达到prevent total loss of the wildflower in its range的目的了，从而也对结论进行了削弱。因此D为答案。

E. 无关。

为什么A是无关选项呢，如果wildflower可以通过其他的方式繁殖的话，异花受粉也就不是唯一的避免绝种的方法了呀？

d就是原题的重复啊（“producing viable seeds”），怎么变成assumption了呢？（而且好象很多assumption题都是选的原题的重复，暂时每找到其他例子）

Try deny test.

Deny A, we get "The wildflower reproduces not only by forming

seeds." However, even so, the wildflower may be still headed for

extinction, since "The population ... is so small". I.e., the

original argument will still stand even if A is denied; therefore A

is not a necessary assumption of the argument.

D is the correct answer. "viable seeds" are just the immediate

results of cross-pollination. But if the wildflower-daisy hybrids

that grown out of the seeds can not reproduce, then the original

argument will fall apart. Therefore, D, "Wildflower-daisy hybrids

will be able to reproduce", is a necessary assumption.