煤巷掘进和采煤工作面应保留的最小预测超前距离均为（）m.。
A、3
B、2
C、1
参考答案：B
Clone science should be developed to benefit human beings ______ harm them.
A．more than
B．other than
C．rather than
D．none other than
立窑看火操作应掌握哪些要领和原则？
