题干

某学习兴趣小组讨论辨析以下说法,其中说法正确的是(   )

①通过化学变化可以实现16O与18O间的相互转化

②灼烧钠的化合物时,火焰呈黄色,发生化学反应

③碱性氧化物一定是金属氧化物

④只由一种元素组成的物质一定为纯净物

⑤石墨和C60是同素异形体

⑥糖类、蛋白质、油脂属于天然高分子化合物.

A:③⑤⑥

B:①②

C:③⑤

D:①③④

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答案(点此获取答案解析)

C

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阅读两篇短文。从每小题所给的四个选项中,选出能回答所提问题或完成所给句子的最佳答案。

It's not WASTE until it is WASTED

    With the World Environment Day coming, our school is now requiring every student to form a habit of sorting the waste.

    Here in our schoolyard we lay four different colors of rubbish bins for different kinds of rubbish. The red is for harmful waste; the blue is for waste that can be recycled(循环再用); the green is for kitchen waste; the yellow is for other waste.

    The following are some instructions for you

    Glass: Empty bottles without caps can be recycled to make new glass bottles.

    Warning: Mirrors and light bulbs(电灯泡) must not be included in the glass waste.

    Paper: Newspapers, magazines, boxes must be clean enough to be recycled.

    Warning: Paper tissues (餐纸) and wall paper are not recyclable as paper and should be kept separately.

    PMD waste: Packaging made of Plastic or Metal and Drink boxes are used to make new packaging.

    Warning: Plastic pots(e. g yoghurt pots ), plastic bags must not be included with the PMD waste.

    Harmful waste: out-of-date drugs, used batteries(电池), paint and oil…

    Besides, if you don't need your old bikes at all, our school volunteers will collect them. We're going to fix them up and then give them away to kids who don't have enough money for a bike.

    To find out more about recycling, you can visit our school website.