问题

The government of the United States began at once toinvestigate the case ______ a lot of students were killed.

A:producing
B:when
C:where
D:why

正确答案是：

同类题型

You can’t complain of being lonely__________ you don’t make an effort to meet people and make friends with them

Much ________ he has a good taste for China’s football matches, he can’t avoid being influenced by the side effects of the football gambling.

It was several minutes before the applaus _____.[ ]

Sam, can I get my umbrella back— Oh, I am very sorry. I ___________ it at home today. I will bring it to you tomorrow.

The air pollution is so terrible.–It will be worse we do something to protect the environment.