我晕了,before,时态() our hair cut before the Spring Festival is a traditional custom in China.是Having还是Having had?答案是Having,但这里有before,为什么不用完成时?

我晕了,before,时态() our hair cut before the Spring Festival is a traditional custom in China.是Having还是Having had?答案是Having,但这里有before,为什么不用完成时? 求 before doing sth的用法?He was sad before doing sth.就是before doing sth 前可以不可以用过去时态.不行的话,那应该如何表示 去电影院前,我去了图书馆.是过去时态. the teacher insisted that we __ our homework before 9:00 o'clocka.finish b.had finished答案是a 但是后面有个before 所以我一开始想的是用完成时态。求高手解答 before用于什么时态 初中英语句子分析（请高手进,we are happy that our country has developed more quickly these years than before.请您帮我分析下这句话 ,包括时态什么的,马上就给分.超级明白我会加分. 关于一般过去式与完成时的两道英语时态题的区分有两道时态题,我有点区分不了.Our teacher _____for 10 years before she came here. A.taught B.had taught C.has taught D.had been taught 答案选B 2. Our new English t It was…before…后面用什么时态呢?我记得是用过去完成时,但是有本书上又说是用一般过去时,我就郁闷了 our hands before eating 我知道填wash告诉我为什么 before后加什么时态 before体现了什么时态?现在完成时?过去完成时?还是什么?请举例说明, 英语句子出现before应用什么时态? before用于句中是什么时态 把“before”放到句末用什么时态? before后面跟什么时态啊 since和before哪个前后时态一致? after before in ago later区别时态 after before in ago later时态区别 before,yet,since一般接什么时态