The old teacher lay wide awake on his bed, all the problems he had to deal with the next day.
A. thought about
B. to think about
C. thinking about
D. having thought about
网友回答
A. thought about
B. to think about
(答案→)C. thinking about
D. having thought about
解析：这位老教师在床上行者想着第二天不得不解决所有问题。考查分词作伴随状语。to do表目的结果，having done发生在位于动作之前。