一道英语选择题（3.12）

题目

一道英语选择题（3.12）
I try to understand ____ that prevents so many Chinese from being as happy as one might expect.
A why is it
B what is it
C why it is
D what it is
这个句子如何翻译,讲一下思路,另请分析一下这个句子的语法结构.
怎么翻译这句话？

答案

不用翻译
还原结构
what is it that prevents so many Chinese from being as happy as one might expect?
如果用why,结构就不完整
因为这句话呢,是做宾语从句,所以it提前,这句话确实是一个强调句