—Is Tom in the next room?

—Well, it’s hard to say. But I heard him_____ loudly when I passed by just now. [ ]

A. speak

B. to speak

C. spoken

D. speaking

（）不是气压制动系统制动不良的原因。

A.制动总泵、制动踏板行程调整不当

B.空气压缩机传动带打滑

C.制动阀调稚不当

D.制动蹄摩擦片沾有油污、水，表面结焦炭化或摩擦片碎裂，磨损过大