Storm chasing is so dangerous that some chasers are often hurt in accidents ______ by driving in a heavy rain.

A．having caused

B．caused

C．to be caused

D．causing

租用的机械设备应选择（）、维修方便和环境影响达标的设备。

A.整机性能差

B.操作方便

C.效率高

D.故障率低