1道高中英语单选.

问题描述:

1道高中英语单选.
I just don`t understand _____ that prevents so many Americans from being as happy as one might expect.
A.why it does
B.what it does
C.what it is
D.why it id

我只是不明白是什么让这么多美国人停止了人所共盼的欢乐.
后面的from being as happy as one might expect就是人所期盼的尽可能的欢乐/幸福.
what is it that prevents…… 是什么阻止了……
懂了没有?