PREP140 (69)

以前没有人讨论，是不是太简单了。

In human hearing, subtle differences in how the two ears hear a given sound help the listener determine the qualities of the sound.

A. in how the two ears hear a given sound help the listener determine

B in the two ears hearing a given sound help the listener in determining  

C in how a sound is heard by the two ears helps the listener determine

D between how the two ears hear a given sound helps the listener in determining

E between how a sound is heard by the two ears help the listener in determining

C,D,E的错误很明显就不说了。答案是A。

PREP注解上解释A中listener 和determine 是双宾语。另外又说help to do sth是固定用法, 这里不是很明白，难道是to省略了？有那位NN可以解释一下。