注意：此页面搜索的是所有试题
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
