He must have gone out. I heard the noise of the door when I was still in bed.A. being lock

问题补充：

He must have gone out. I heard the noise of the door when I was still in bed.

A. being locked

B. to lock

C. locking

D. having locked

答案：

(答案→)A. being locked

B. to lock

C. locking

D. having locked

解析：考查非谓语动词和固定用法。句意“他一定是出去了。当我没起床时，我就听见了锁门声。”door和lock之间是被动关系，应该用被动语态。hear sb./sth. doing sth.“听到正在做某事”。故选A。