I supported him in time otherwise heoff the bike .A. might fall B. would fall C. should

问题补充：

I supported him in time , otherwise heoff the bike .

A. might fall

B. would fall

C. should have fallen

D. would have fallen

答案：

A. might fall

B. would fall

C. should have fallen

(答案→)D. would have fallen

解析：otherwise 否则，相当于if not。本句可改为： if I hadn’t supported him in time, he off the bike。显然，这是与过去事实相反，主句应用would/could…+have done。故选D。