问题
选择题
It was not until 3 days later that the boy came back to life and explained to the police what_______ to him.
A．was happening
B．was to happen
C．had happened
D．has happened
答案
答案：C
考查时态。句意为：两个星期后，那个男孩才苏醒过来，向警方解释到底发生了什么事。happen发生在explain之前，是“过去的过去”，用过去完成时。