He pretended when his mother stepped into the room..A. to studyB. studyingC. to be studyin

问题补充：

He pretended when his mother stepped into the room..

A. to study

B. studying

C. to be studying

D. to have studied

答案：

A. to study

B. studying

(答案→)C. to be studying

D. to have studied

解析：考查不定式用法。不定式的一般式to do说明该动作在谓语动词之后发生；进行时to be doing表示两者同时发生；to be done表示被动；句意：当他的妈妈走进房间的时候，他假装在睡觉。根据句意说明两个动作同时发生，故使用不定式的进行时。故C正确。

考点;考查不定式用法