问题
填空题
用 when或 while填空。
1. I was looking out of the window _________ the teacher asked me.
2. What is he doing _________ his parents came back？
3. Mike was playing games _________ Jack was studying.
4. I was about to fall asleep _________ the baby began to cry.
答案
1. when 2. when 3. while 4. when