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问题 填空题

硅酸盐晶体分类的依据是______。按此分类法可将硅酸盐矿物分为：______结构、______结构、______结构和______结构。

答案

参考答案：[SiO4]连接方式；岛状；组群状；链状；层状或架状

单项选择题

Over the past two years, a firm reported higher operating cash flow as a result of securitizing its accounts receivable and from increasing income tax benefits from employee stock options. The tax benefits are solely the result of higher tax rates. Should an analyst conclude that these two sources of operating cash flow are sustainable()

A. Both sources are sustainable.

B. Neither source is sustainable.

C. Only one of these sources is sustainable.
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填空题

下列物质中含有极性键的是______，含有非极性键的是______，属于非极性分子的是______，属于极性分子的是______．（用序号填空）

①CO2    ②H2O   ③CH4    ④N2   ⑤H2    ⑥Na2O2   ⑦NaOH    ⑧HF   ⑨NH3．
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