砌碹巷道（主要巷道）净宽（中线至任一帮）的合格标准为（）mm，优良标准为（）mm。
A、-30～+50
B、0～+50
C、0～+30
参考答案：B, C
—Are you going to Shanghai?
—Yes, we _____ Shanghai next Sunday. [ ]
A. are leaving for
B. are leaving
C. leave for
请简述存货的主要功能？存货的功能具体体现在以下各个方面：
