问题补充：
Will was stupefied with exhaustion, and he his head on the grass under one of the trees and slept, but he saw a cat acting strangely.
A. should have lied
B. ought to have lay
C. might have laid
D. must have laid
答案：
A. should have lied
B. ought to have lay
(答案→)C. might have laid
D. must have laid
解析：句意：Will过度劳累，他本来可能已经将头枕在树下的草地上睡着了，但是他看见一只猫走过来。这里表示对过去的事情的不太肯定的推测，用might have done，should have done是虚拟语气“过去本应该做却没有做”，ought to have done和should have done意思一样，也是“过去本应该做却没有做”，must have done“过去一定做了…”。所以选C。
