什么是选煤工艺？
参考答案：
指从接受原煤起到产品装车止按照一定顺序联系起来的各种加工作业和辅助作业的总合。
If you ______to her about it yesterday, you ________ what to do now. [ ]
A. should have spoken; would know
B. spoke; would know
C. had spoken; would have known
D. had spoken; would know
在一定温度下，导体的电阻与导体的长度成（），与截面积成（），与导体的材料有关。
