when或while引导的时间状语从句,主句为祈使句或含有情态动词,从句什么时态?

1 如果你会合并下列句子,你的这个问题就OK了：He came She was wating 1 When he came,she was waiting2 While she was waiting,he came3 She was waiting when he came4 He came while she was waiting 2 主句为祈...