关于 时间状语从句.句型装换.

题目

关于 时间状语从句.句型装换.
1.I knew it after he told me.
I _____ ______ it ______after he told me.
用after.主句与从句的时态是怎么样的.
2.We don't enter the classroom until the bell rings.
We ______ the classroom ______ the bell rings.
Wanghai didn't stop working until he fell ill.
Wanghai ______ ______ _______ he fell ill.
还是时态搞不清.
时态总不知道用什么.

答案

1,didn't know until
2,enter after
3,stopped working after