I while reading the English textbook. Luckily, my roommate woke me up in time!
A. had fallen asleep
B. have fallen asleep
C. fell asleep
D. fall asleep
网友回答
A. had fallen asleep
B. have fallen asleep
(答案→)C. fell asleep
D. fall asleep
解析：while 从句用过去进行时，主句用过去时，表示在某个动作的持续过程中，发生过某事。句意为“我在读英语课本时睡着了。幸亏我的室友及时叫醒了我”。