使用万用表测量电压的方法是（）。
A、指针归零
B、先选择偏小量程档位
C、先选择大量程档位
D、测试棒置于规定插孔内
参考答案：A, C, D
Some economists predict that the dollar will remain weak _______ economies abroad are expected to
grow faster than that of the United States. [ ]
A. while
B. as
C. before
D. until
中矿是指在选别过程中，除精矿和尾矿之外的半成品。
