用after或before

用after或before 用before或after连接过去的两个句子时,before 和after各用什么时态 请问after和before后面的动词要用ing吗?比如after he leaving 或before he leaving 英语翻译要用.after..before..but. before和after一定要用过去式吗? BEFORE AFTER怎么样 BEFORE DOING和AFTER Before the police arrived,the alien left the shop ,句中能用when或after代替before吗,为什么? before 或after 在句子中间时应跟上句连着翻译还是下句. while,when,until,after,before,as soon as 怎么用? 英语翻译请分别用till until after before 翻译 after和before的用法 when,while,before,after+________ before,after的区别怎样用. 以before或after引导的状语从句有问!进入帮手例：It will be four days before they come back哪句系主句?哪名是从句? The awards start.We will interview some of the most famous starts.(选用after或before连接） The Japanese will not leave China until /after/before/when she finishes her study,哪一个,为什么用after/before/when 时句子要怎么改 soon after,after a while 和 before long 三个的区别是什么?分别怎么用?后面怎么跟?