Weight is considered during the periodic required inspection and servicing of().
A. CO2 (carbon dioxide) fire extinguishers
B. foam fire extinguishers
C. water (stored pressure) fire extinguishers
D. All of the above
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流过电流的路径称电路.()
A. 正确
B. 错误
矿用高强度园环链分A、B、C、D等4级.()
A. 正确
B. 错误
公路中线测量中,设置转点的作用是()。
A传递高程;
B传递方向;
C加快观测速度