问题

Look, so many people are running out of the station. I wonder what ________.
A:is happened
B:was happening
C:is happening
D:had happened
B:was happening
C:is happening
D:had happened
正确答案是:
同类题型
Is her pen the same _______yours?[ ]
.I have no idea________is better, so I took of them.
You are always telling me I am lazy. Look at your room. What a mess it is! ________.
Have you read the news _____ the newspaper?[ ]
In order to find ____ better job, Tom made up his mind to learn ____ second foreign language.