When his mother came home he pretended sound.A. sleepingB. to sleepC. to have sleptD. to

问题补充：

When his mother came home, he pretended sound.

A. sleeping

B. to sleep

C. to have slept

D. to be sleeping

答案：

A. sleeping

B. to sleep

C. to have slept

(答案→)D. to be sleeping

解析： 考查短语：假装正在做某事pretend to be doing sth，句意：当他的母亲到家的时候，他在假装熟睡。to sleep动作还没发生，to have slept动作发生在谓语动词之前，故选D。