A．did not happen
B．hadn't happened
C．haven't happened
D．would not happened

A.did
B.hadn't
C.haven't
D.would

【参考答案】

B
解析：hadn'thappened，注意此处的过去虚拟语气：要是眼前这一切不曾发生，让他们做什么他们都愿意。