He was a teacher before,but he isn't now He is_____a teacher 意思是他以前是老师,但现在不是了怎么改
还有情态动词：
1.Need I do the washing-up?I'm in a hurry.
______do the washing-up?I'm in a hurry.
2.You must tell Jennifer all about it.
You_______tell Jennifer all about it.
3.My daughter can jump quite high.
My daughter_____jump quite high.