what surprised me a lot was that he didn't know ______ the difference between “tell”and “ask”.

问题描述:

what surprised me a lot was that he didn't know ______ the difference between “tell”and “ask”.
A :what B :that C :where D :which
选A难道不行吗?意思就是“……不知道两者的不同是什么……”

选A的话 句子宾语从句缺成分
如选A应是what surprised me a lot was that he didn't know what is the difference between “tell”and “ask”.