Question

when引导的从句和主句用什么时态

Answer 1

1.when引导的时间状语从句，遵循主将从现原则
如 I will tell you When he comes back.
当他回来时我会告诉你。
2.前后时态要一致
如
He could swim when He was two years ago.他两岁时会游泳。
3. 当一个动作发生（一般过去时），另一个动作正在进行（过去进行时态）
如
The students were talking when the teacher came into the classroom.
老师就进教室的时候，学生们正在说话。