阅读 tpo11 第三篇的4,5题 - Begging by Nestlings

chasedream0000

Begging by Nestlings这篇阅读的第二段涉及到第4,5两题，这两题都选错了，看了答案还是不明白，估计是自己的理解还没通。求帮忙解答啊  

◆ Further evidence for the costs of begging comes from a study of differences in the begging calls of warbler species that nest on the ground versus those that nest in the relative safety of trees. The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives. These higher-frequency sounds do not travel as far, and so may better conceal the individuals producing them, who are especially vulnerable to predators in their ground nests. David Haskell created artificial nests with clay eggs and placed them on the ground beside a tape recorder that played the begging calls of either tree-nesting or of ground-nesting warblers. The eggs “advertised” by the tree-nesters' begging calls were found bitten significantly more often than the eggs associated with the ground-nesters' calls.

4. Paragraph 2 indicates that the begging calls of tree nesting warblers
○ put them at more risk than ground-nesting warblers experience
○ can be heard from a greater distance than those of ground-nesting warblers
○ are more likely to conceal the signaler than those of ground-nesting warblers
○ have higher frequencies than those of ground nesting warblers

5. The experiment described in paragraph 2 supports which of the following conclusions?
○ Predators are unable to distinguish between the begging cheeps of ground-nesting and those of tree-nesting warblers except by the differing frequencies of the calls.
○ When they can find them, predators prefer the eggs of tree-nesting warblers to those of ground-nesting warblers.
○ The higher frequencies of the begging cheeps of ground-nesting warblers are an adaptation to the threat that ground-nesting birds face from predators
○ The danger of begging depends more on the frequency of the begging cheep than on how loud it is.


答案：4B 5C

CRD

The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives. These higher-frequency sounds do not travel as far……
地鸟频率比树鸟高。这些高频率声音传地不远（注意：是as far，与……一样远，其实暗指没有树鸟远）所以选B
may better conceal the individuals producing them, who are especially vulnerable to predators in their ground nests. ……The eggs “advertised” by the tree-nesters' begging calls were found bitten significantly more often than the eggs associated with the ground-nesters' calls.
说明树鸟声更容易遭到袭击，但是地上要比树上危险（differences in the begging calls of warbler species that nest on the ground versus those that nest in the relative safety of trees），为什么实验里树鸟蛋破坏更多呢（注意：树鸟蛋和地鸟蛋都放在了地上）？这说明地鸟的声音具有adaption to a threat,可以认为是因为住在更危险的地方而进化出来了一种不同叫声来降低危险。