问题
选择题
We still don’t know what _________ while we were away from home.
A．had happened
B．was happened
C．has happened
D．happened
答案
D
题目分析：句意：我们仍然不知道在我们离开家时发生了什么。Happen发生，是一个不及物动词。根据while we were away from home可知该用一般过去时，所以选D。