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：B 考察虚拟语气。句义：我及时扶住了他，要不然他就会从自行车上摔下来。根据题干中的otherwise he would have fallen off the bike可数是对过去事实进行虚拟，所以使用一般过去时。故B正确。