电刷火花的等级有()级。
A、4
B、5
C、6
D、7
参考答案:B
All of them felt it necessary that they______ __the meeting
A.attend
B.would have attended
C.attended
D.were to attend
列车发生火灾系指列车起火造成机车车辆破损影响行车设备正常使用,或发生人员伤亡、货物、行包烧毁等。