题目

下列实验能达到实验目的是（ ） A. A    B. B    C. C    D. D 答案：【答案】D 【解析】A、第一支试管中的铁钉能与氧气、水充分接触；第二支试管中的铁钉只能与水接触；一段时间后，第一支试管中的铁钉生锈；第二支试管的铁钉没有生锈；能说明铁生锈与氧气有关，无法确定铁生锈是否与水有关，实验不能达到实验目的；B、白磷与氧气接触，白磷能燃烧，红磷与氧词形变化 根据所给单词和句意，用适当的词填空，在答题卷上标有题号的横线上，写出空缺处各单词的正确形式。每空只写一词。1.We can clean our desks and chairs first and help to clean later．(they)2.My brother is fixing my computer．(break)3.The boy is very and he often leaves his keys at home．(care)4.People in America use forks and when they have dinner．(knife)5.His grandfather fell off the bicycle and was hurt．(bad)