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【简答题】
（1）把下列物质用途所依据的相关物质的性质填写出来： ①金钢石用于裁玻璃是因为______； ②一氧化碳用于冶金工业是因为______； ③干冰用于人工降雨是因为______． （2）经研究发现NH 3 燃烧的产物没有污染，NH 3 中氮元素的化合价为______价．请将NH 3 燃烧反应的化学方程式补充完整：4NH 3 +3O 2 点燃 . 6H 2 O+______． （3）自然界的水需要经过沉降、______、吸附，消毒等多步净化处理成为城市生活用水（即自来水）．自来水中仍含有一些可溶性杂质，含有较多的可溶性钙和镁的化合物则为硬水．可用来区分硬水和软水的试剂是______．实验室所用净化程度较高的通过______（填分离方法）制取． （4）塑料袋曾给我们的生活带来很大方便，但却造成了严重的环境问题． ①塑料属于______（填“天然”或“合成”）材料； ②聚乙烯塑料完全燃烧产生二氧化碳和水，由此可知聚乙烯塑料中一定含有______元素； ③从环境或能源角度，谈一点限制生产和使用塑料购物袋的意义：______．
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举一反三
【单选题】Tsui attended Yale University, where he was a member of Davenport College and The Duke's Men of Yale, an all-male a cappella group. He also majored in ______ at Yale University.
A.
Classical Music
B.
Classical Greek
C.
Computer Programming
D.
Finance
【简答题】A．Princeton. B．Yale. C．Harvard. D．Stanford.
【简答题】Yale is composed of______ colleges.
【简答题】Yale University is named after Elihu Yale, who once worked for EIC as ______.
【简答题】All urgent matters have now been ______. A) attended B) attended to C) attended at D) to attend
【单选题】We didn't see Tom at the meeting yesterday. He ________it. A. mustn't have attended B. cannot have attended C. needn't have attended D. would have not attended
A.
mustn't have attended
B.
cannot have attended
C.
needn't have attended
D.
would have not attended
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