出自: 真题阅读88篇
原文:
Passage 13
Biologists have long debated about whether egg production in birds is biologically highly costly,some theorizing that egg production is energetically or nutritionally demanding. Lack, however,suggested that clutch size—the number of eggs a bird lays per breeding cycle—is far below the potential limit of egg production. He suggested that clutch size had instead evolved in relation to the number of young that the parents could successfully rear. Subsequently, most studies focused on limitations operating during chick rearing, particularly among altricial species (species in which the parents feed their young in the nest). Lack later recognized that in precocial species (species in which young feed themselves), clutch size might be explained by different factors—the availability of food for egg-laying females, for example.
问题是:Consider each of the choices separately and select all that apply.
2. The passage suggests that Lack would agree with which of the following statements about
factors affecting clutch size in birds?
A. In altricial species, clutch size is determined primarily by factors operating after eggs are laid.
B. In precocial species, clutch size is determined primarily by factors operating after eggs are laid.
C 是对的, 就不给啦。
你的理解是对的,问题的关键在于“能养活几个”到底算不算是“factors operating after eggs are laid”。虽然说“能养活几个”确实取决于蛋生下来之后的环境,但比较纠结的点在于,parents在产这些蛋之前显然是不可能知道这些情况的,所以它们的决定实际取决于对蛋生下来后环境的“估计”,而这个“估计”,又显然是在蛋生下之前发生的了。
不过看到原文后面一句话,你就知道这道题是怎么回事了:
Subsequently, most studies focused on limitations operating during chick rearing, particularly among altricial species (species in which the parents feed their young in the nest).
和factors operating after eggs are laid完全对应,A选项就是从这句话里出出来的。