He fell asleep when he was reading when之后可以接过去进行时吗

He fell asleep while___his exercises. fell asleep等于什么? They _ down and soon fell asleep. as soon as I fell asleep是什么意思 sleep与fell asleep有什么分别 He fell off the ladder. The girl fell asleep ______ doing her english exercises. 谢谢 John fell asleep ___he was listening to the music Lucy fell asleep at nine o’clock last night. Tom fell asleep _____ a few books open