各位老师，我就想确定一下，第一句是对的，对吧，
What I'm not sure about is when you don't do it
What I'm not sure about is when you not do it
由于一定式的时候去掉了助动词do，否定式我不太确定，
What I'm not sure about is when you don't doit. 正确
What I'm not sure about is when you not do it. 错误
这是所谓的“假拟分裂句”，强调when从句。不强调的普通句式为：
I'm not sure when you don't do it.
他们一直做某事（you always doit). 所以说话人不可以确定他们什么时间不做此事。独立的特殊问句为：When don't you do it?
原第二句when从句否定没用操作词为语法错误。
