第2个回答 2013-04-21
a.时间状语从句
when//as soon as/before/after/not…until/as
主将从现,
主过从过 同时 持续 过去进行式
瞬间 一般过去式
先后 先 过去完成式
后 一般过去式
While 从句用 进行时(持续动词)或持续的状态
Since 主句现在完成时,从句过去式(主句有一段时间,可用一般现在时来代替)
出现进行时态, 在 when/while 两者里选择
When the teacher came into the classroom , we began to read the books.
When the teacher came into the classroom, we were reading the books.
While the teacher was correcting the homework, we were reading the books.
When the teacher came into the classroom, we had handed over our homework.