76. Learning how to build a nest plays an important part in the breeding success of birds. For example, Dr. Snow has recorded the success of a number of blackbirds in several successive years. He finds that birds nesting for the first time are less successful in breeding than are older birds, and also less successful than they themselves are a year later. This cannot be a mere matter of size and strength, since blackbirds, like the great majority of birds, are fully grown when they leave the nest. It is difficult to avoid the conclusion that they benefit by their nesting experience.

Which one of the following, if true, would most weaken the argument?

(A) Blackbirds build better nests than other birds.

(B) The capacity of blackbirds to lay viable eggs increase with each successive trial during the first few years of reproduction.

(C) The breeding success of birds nesting for the second time is greater than that of birds nesting for the first time.

(D) Smaller and weaker blackbirds breed just as successfully as bigger and stronger blackbirds.

(E) Up to 25 percent of all birds are killed by predators before they start to nest.

正确选项为B, 但个人觉得D也是一个不错的选项阿。。

请教。

对这种most weaken的题总不太拿得准，觉得有些选项之间的程度很难区分

好好读读原文，作者进行的是对不同年龄的鸟的比较，而不是对他们的身体情

况的比较。D是无关的。

对阿， D选项中 smaller and weaker和 bigger and stronger不正是对身体情

况的比较么？

这道题我的看法是，D是加强。因为提到This cannot be a mere matter of size and strength，不仅仅是大小和力量的关系，那么如果 Smaller and weaker blackbirds breed just as successfully as bigger and stronger blackbirds.，说明作者的说法正确，必然有其他原因导致结论。该原因就是经验。所以是加强。

谢谢，对这道D的无关能够理解了，偶看题的时候只注意到了strength and

size, 故而就误以为是在对身体状况的讨论，仔细再看，才看出strength and

size实际上是年龄的标志。