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题目内容
（河北工业大学-英语3）
We have sometimes accidents on this line, but no accident______since last winter.(本题1.0分)
A、 has been occured
B、 has occurred
C、 has been occurring
D、 is occurring
A、 has been occured
B、 has occurred
C、 has been occurring
D、 is occurring
参考答案
