汽车维修标准体系第二层次为专用修理技术标准，也可称为（）。
A.产品标准
B.技术管理标准
C.方法标准
参考答案：C
According to the latest reports on TV and in the newspaper, food safety is
becoming a ________ serious worldwide problem. [ ]
A. more and more
B. little by little
C. now and then
D. one by one
国家标准规定，电雷管的安全电流为（）。
A．0.05A
B．0.15A
C．0.45A
