DF4C机车基础制动装置检修时，各销套的径向间隙不大于（）。
A、1
B、2
C、3
D、4
参考答案：B
What the teacher said at the meeting _______very helpful to us.
A turned to B. turned from C turned out D. turned up
Don’t _____ to correct me if I made a mistake.
A．pause
B．stop
C．mind
D．hesitate
