after为什么有时候要用主将从现,如：After he gets back,he will do his homework.而有时候又不要用,如
问题描述：
after为什么有时候要用主将从现,如：After he gets back,he will do his homework.而有时候又不要用,如
After I leave school,I want to visit Beijing.为什么,理由?
答
区别在于want是现在的动作,并不是leave school以后才有的动作.
而do homework是get back以后的动作,所以要用将来时.