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
How do you go to school? —I go to school _____. [ ]
_____ a year does your school have sports meetings?—Twice a year. [ ]
I pretended ________her when I walked by.
More and more foreigners are working in China, ______?
It’s reported that ________ young ____ to be rebellious against ____ parents’ instructions nowadays.