when did the accident happen?_____a winter morningA:in   B:At    C:On     D:For

问题描述:

when did the accident happen?_____a winter morningA:in   B:At    C:On     D:For

A(肯定的)

正确答案是happened用一般过去时态.六楼的解释很到位.事故的发生都用happen B B 选择B A项意思不对 C项可改成happened A B 都可以