保护接地就是将电气设备正常运行时不带电的金属外壳和()之间作良好的()。
参考答案:接地装置;电气连接
— May I go out and play this afternoon?
— No, you _____. Work comes first [ ]
A. needn't
B. mustn't
C. won't
D. don't
125×A×8=A×(125×8)运用了乘法( )律。