录用人员数量评估主要从三方面进行,分别为录用比、()和招聘完成比。
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When used to fight fire,carbon dioxide().
A. is effective if used promptly on an oil fire
B. has a greater cooling effect than water
C. is lighter than air
D. is harmless to cargo and crew
氧在钢中几乎全部以氧化物夹杂形式存在。
A. 正确
B. 错误