问题

—What areyou busy with — We are carrying out a research ____ thecauses of cancer
A:As she won
B:Won
C:Winning
D:Because of winning
B:Won
C:Winning
D:Because of winning
正确答案是:
同类题型
The new headmaster looks _________ to all the teachers and students of the school.
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I was doing my homework_______ the telephone rang. It was my aunt.