某地1，000Kg化肥的市场价格如下：CO（NH2）21，780元、NH4NO3_爱下问搜题

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问题问答题

某地1，000Kg化肥的市场价格如下：CO（NH₂）₂ 1，780元、NH₄NO₃ 1，360元、NH₄HCO₃（碳酸氢铵）560元．分别用10，000元采购上述化肥，则购得化肥中含氮元素最高的是哪一种？

答案

10000元钱能买CO（NH₂）₂的质量为：

10000元

1.78元/kg

≈5618.0kg

5618.0kgCO（NH₂）₂中氮元素的质量为：5618.0kg×

14×2

12+16+(14+1×2)×2

×100%≈2621.7kg；

10000元钱能买NH₄N0₃的质量为：

10000元

1.36元/kg

≈7352.9kg

7352.9kgNH₄N0₃中氮元素的质量为：7352.9kg×

14×2

14+1×4+14+16×3

×100%≈2573.5kg；

10000元钱能买NH₄HC0₃的质量为：

10000元

0.56元/kg

≈17857.1kg

17857.1kgNH₄HC0₃中氮元素的质量为：17857.1kg×

14

14+1×4+1+12+16×3

×100%≈3164.6kg；

三者相比较 3164.6kg＞2621.7kg＞2573.5kg

故碳酸氢铵含氮量最高

答：含氮元素最高的是碳酸氢铵

完形填空

请阅读下面短文，选择最佳答案，将其标号在答题卡上涂黑。
There are many kinds of friends. Some are always        you, but don't understand you. Some say only a few words to you, but understand you. Many people will step in your life, but only        friends leave footprints.
I shall always recall the autumn and the girl with the        . I know she will always be my best friend. I could see the yellow leaves         in the cool wind. In such a        , I liked walking alone in the leaves,         to the sound of them. Autumn is a harvest season. However,         is uninteresting. The free days always get me      . But one day, the sound of a violin       into my ears like a stream flowing in the mountains. A young girl, standing in the wind, was        in playing her violin. I had        seen her before. The music was so nice that I listened quietly. Lost in the music, I didn't know that I had been     _ there for so long but my existence(存在) did not seem to disturb（打扰）her.
Every day she played the violin in the corner of the building        I went downstairs to watch her performance. The autumn seemed no longer lonely and life became       . Though we didn't know each other, I thought we were already good       .
One day, when I was listening carefully, the sound suddenly       . To my surprise, the girl came over to me. “You must like violin，” she said. “Yes. And you play very well. Why did you stop?” I asked. Suddenly, a        expression appeared on her face and I could feel something unusual. “I came here to see my grandmother, but now I must leave, I once played very badly. It was your listening every day that       me,” she said. “In fact, it was your playing        gave me a meaningful autumn，” I answered, “Let's be friends.” The girl smiled, and so did I.
I never heard her play again in my life. But I will always remember the fine figure(身影) of the girl. She is like a       －so short, so bright, like a shooting star giving off much light that makes the autumn beautiful.

A．interesting

单项选择题

我国将危险化学品按其危险性分为（）类。

A.8

B.9

C.15

D.6