常用管件不包括（）
A.弯头
B.阀门
C.三通
D.法兰与盲板
参考答案：B
The new minister is taking measures aimed at the economy to full strength.
A．seizing
B．restoring
C．striking
D．casting
用激光指向仪指示巷道掘进方向时，应遵守哪些规定？
