PREP 23题

白菜白菜

23.    (25612-!-item-!-188;#058&002525)

Scientists believe that unlike the males of most species of moth, the male whistling moths of Nambung, Australia, call female moths to them by the use of acoustical signals, but not olfactory ones, and they attract their mates during the day, rather than at night.

(A) by the use of acoustical signals, but not olfactory ones, and they attract
(B) by the use of acoustical signals instead of using olfactory ones, and attracting
(C) by using acoustical signals, not using olfactory ones, and by attracting
(D) using acoustical signals, rather than olfactory ones, and attract
(E) using acoustical signals, but not olfactory ones, and attracting




答案是D 为什么by都不需要了？

mslancaster

因为主动发出的动作不一定需要加by，using这里做v-ing使用，表示持续发生的某事。 而且attract和call平行一致，D是唯一可选答案。A有they指代不清嫌疑。

白菜白菜

因为主动发出的动作不一定需要加by，using这里做v-ing使用，表示持续发生的某事。 而且attract和call平行一致，D是唯一可选答案。A有they指代不清嫌疑。

-- by 会员 mslancaster (2012/3/26 14:16:37)

嗯嗯 懂了 谢谢啦~