用火花鉴别钢材时,()是引起大火的主要元素,随含碳量的增加火花增多、高度增加。 A. 发布时间:2017-08-12 09:56 │ 来源:www.tikuol.com 题型:单项选择题 问题: 用火花鉴别钢材时,()是引起大火的主要元素,随含碳量的增加火花增多、高度增加。A.碳B.铁C.锰
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题型:单项选择题 .Not ____ he died, he received an award for his selfless service to the old.A.long beforeB.before longC.long agoD.shortly before 查看答案