问题

One thing’s for sure, the fire _____by some cigarette butts.
A:might cause
B:could have caused
C:must have been caused
D:should be caused
B:could have caused
C:must have been caused
D:should be caused
正确答案是:
同类题型
With time ________ by, they got to know each other better.
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ther _______ football quite well, but hehasn’t played since last year
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I’d like a cup of black coffee. What about you, Mike— I prefer coffee __________sugar.