（）能提高爆破的炮孔利用率，减小岩石的块度，降低炸药单耗和提高爆破效果。
A、正向爆破
B、中间爆破
C、反向爆破
参考答案：C
The system has been designed to give students quick and easy ________ to the digital resources
of the library.[ ]
A. access
B. passage
C. way
D. approach
滑车的轮轴磨损到轴公称直径的3%～5%时，要更换新轴。
