A. 不同国家、地区和单位水平之间的比较 B. 先进水平与落后水平的比较 C. 不同时期水平的比较 D. 实际水平与计划水平的比较实际水平与标准水平或平均水平的比较
A. 正确 B. 错误
A. 7% B. 10% C. 15% D. 25%
A. couducts electricity B. should be directed at the base of the fire C. is most effective on burning gases which are flowing D. extinguishes by cooling oil fires blow ignition temperature
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