死猴子題，先前上課的講法我想要再重新修正一下，也就是我對答案D的解釋。
37. (32356-!-item-!-188;#058&006101)
“Capuchin monkeys in Venezuela often rub a certain type of millipede into their fur.” Secretions of these millipedes have been shown to contain two chemicals that are potent mosquito repellents, and mosquitoes carry parasites that debilitate the capuchins. (The rubbing behavior is rare except during the rainy season, when mosquito populations are at their peak.) Therefore, “the monkeys probably rub the millipedes into their fur” because doing so helps protect them against mosquitoes.
Which of the following would it be most useful to determine in order to evaluate the argument?
(A) Whether the two chemicals provide any protection for the millipedes against their own predators
(B) Whether the type of millipede used by the capuchin monkeys in Venezuela is found in other parts of the world
(C) Whether animals other than capuchins rub insects of any kind into their fur
(D) Whether the only time the millipedes are readily available to the capuchins is during the rainy season
(E) Whether secretions of any other insects accessible to the capuchins contain chemicals that repel mosquitoes
這題真的很盧，因為若題幹去掉括號部分，一樣也可以下結論。
Capuchin monkeys in Venezuela often rub a certain type of millipede into their fur. Secretions of these millipedes have been shown to contain two chemicals that are potent mosquito repellents, and mosquitoes carry parasites that debilitate the capuchins. Therefore, the monkeys probably rub the millipedes into their fur because doing so helps protect them against mosquitoes.
所以重點來了，那句括號確實對題幹產生重大影響，重點在於Often和rare，題幹說明猴子經常去抓millipedes來rub，但是除了雨季外很少抓millipedes來rub(這就是很盧的地方，題幹資訊感覺有衝突在，經常rub現在又變成只在雨季才做這件事)，然後根據這個事實，下結論說磨millipedes是為了防蚊。
答案D把millipedes可取得時間限縮在雨季，若不限縮在雨季，非雨季時期因為Capuchin monkeys in Venezuela often rub a certain type of millipede into their fur.這句事實，會讓Capuchin monkeys 在非雨季繼續磨millipedes，但是非雨季蚊子少，抓millipedes磨的目的可能就不是防蚊，而是其他目的(可能是拿來玩或者是當古龍水吧?)。
硬要說起來這題可以算是斷橋型的題目，斷橋型的題目通常答案都很難選，畫一下推理鏈吧:
題幹:
Only rainy season---Mosquito
結論:
(Rub) Millipedes---(防) Mosquito
答案:
Only rainy season---Millipedes
這個答案符合GMAC正確答案模式。
