电池由电解液和其中两种不同材料的电极组成，一般电极由锌片和（）组成.
A.铜棒
B.铁磁棒
C.碳棒
D.铅棒
参考答案：C
-When will you go back to your hometown? - _______.
A．Until the work is finished
B．Not until the work is finished
C．After the work will be finished
D．As soon as the work will be finished
在检修过程中（）点必须由监理人员到现场检查签字认可后才能进入下一道工序
A.W
B.H
C.V
D.R
