when+时间状语从句，从句时态用法，以及过去进行时用法

可以参考《结束蹦单词时代：外教教你用连词》，中国书籍出版社，第165-167页：

1. When he sleeps, he often sucks his thumb.
2. I always drink coffee when I work.
3. When he gave me a present, I thanked him.
4. She cuddled her teddy bear when she went to sleep.
5. When I am studying, my dog sits under the desk.
6. I usually set the table when my mum is cooking the dinner.
7. When I was walking along, I came across a friend of mine.
8. My friend waved to me when I was cycling past.
9. When I have finished my studies, I am going to work abroad.
10. I shall give you a call when you have finished work.
11. When they had finished eating their meal, the guests moved to the lounge for some coffee.
12. The cat looked terrified when I had found her.
13. When driving, wear your seat belt.
13. I saw a squirrel in the park when going for a jog.

when 引导的从句可以用一般现在时（主句用一般现在时）、一般过去时（主句用一般过去时）、现在进行时（主句用一般现在时）、过去进行时（主句用一般过去时）、现在完成时（主句用将来时），或过去完成时（主句用一般过去时）。when 后面还可以去掉“主语＋be”，直接用动名词（主句用一般现在时或一般过去时）。

可以一般过去，与此区别的while则不可以