I him in time otherwise he would have fallen off the bike.A. had supportedB. supportedC.

问题补充：

I him in time, otherwise he would have fallen off the bike.

A. had supported

B. supported

C. have supported

D. Support

答案：

A. had supported

(答案→)B. supported

C. have supported

D. Support

解析：此题考察了时态和虚拟语气。从后面分句可知这是对过去时的虚拟，因此用过去式。