GWD3-Q38: Kate: The recent decline in numbers of the Tennessee warbler, a North American songbird that migrates each fall to coffee plantations in South America, is due to the elimination of the dense tree cover that formerly was a feature of most South American coffee plantations. Scott: The population of the spruce budworm, the warbler’s favorite prey in North America, has been dropping. This is a more likely explanation of the warbler’s decline. Which of the following, if true,most seriouslycalls Scott’s hypothesis into question? - The numbers of the Baltimore oriole, a songbird that does not eat budworms but is as dependent on
South American coffee plantations as is the Tennessee warbler, are declining. - The spruce-budworm population has dropped because of a disease that can infect budworms but
not Tennessee warblers. - The drop in the population of the spruce budworm is
expected to be only temporary. - Many Tennessee warbler have begun
migrating in the fall to places other than traditional coffee plantations. - Although many North American
songbirds have declined in numbers, no other species has experienced as great a decline as has the Tennessee warbler. 答案是D,我想請問C為什麼是無關? 請高手解答,謝謝~~~
我自己的解釋如下: A 無關比較,有果無因。 B 無關比較。蟲得病會減少,但是此病對鳥沒有影響。 C 蟲減少的原因只是暫時的,但鳥數量持續減少,表示鳥減少的數量另外有其他原因。我這樣認為,但是這樣的思維似乎有錯. D 的答案並沒有牽涉到蟲子的減少, 其實是可以解釋鳥變少的原因,但並不是針對Scott提到的論點而加以削弱,所以一開始實在沒辦法選這答案. E 擴大範圍,無關比較。題目只問Tennessee warbler減少的原因,沒問到其他鳥。
[此贴子已经被作者于2008-11-24 2:27:35编辑过] |