深孔爆破在爆区侧面设施移出距离为()米。
A.20
B.30
C.50
D.100
参考答案:C
Dogs are clever animals and they can be trained to ________ houses. [ ]
A. look for
B. watch
C. watch out
D. watch out for
调质能得到韧性和()最好的配合,获得良好的综合力学性能。