_______they are closest friends is not clear though they live together.

问题描述:

_______they are closest friends is not clear though they live together.
A.That B.If C.What D.Whether
选什么,

选D “is not clear” 意味着“不清楚” 所以选择中文意思为“是否”的单词 即c或者d ,但if不能引导主语从句,whether可以引导,所以选d
这句话的意思是 即使他们住在一起,别人也不能确定他们是否是朋友.