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问题 选择题

下列反应不属于氧化还原反应的是（    ）

A．2Na2O2＋2CO22Na2CO3＋O2

B．Ca(O H)2＋2NH4ClCaCl2＋2NH3↑＋2H2O

C．Fe2O3＋3CO2Fe＋3CO2[来源]

D．Cu＋2H2SO4（浓）CuSO4＋SO2↑＋2H2O

答案

答案：B

氧化还原反应的本质是电子的转移，特征是反应前后化合价发生变化。A中过氧化钠中的氧元素化合价由—1价部分升高到0价，部分降低到－2价，属于氧化还原反应。B中元素的化合价均没有变化，不属于氧化还原反应。C中铁和碳的化合价发生了变化，D中铜和硫的化合价发生了变化，它们均属于氧化还原反应。答案是B。

阅读理解

根据短文内容，完成下列各题.每空词数不限。

     Hello! My name is Li Lei. There are four new students in our school. They are from America,

England, Canada and Australia. They speak English and French. But they can't speak Chinese. We

usually talk with them in English. We are good friends. They like Chinese food very much. Dumplings

and noodles are their favourite. They like playing games (玩游戏) with Chinese students. We usually

play football (踢足球) after school. They think (认为) China is great and they like China very much.

1. The boy's name is _________ and he has _________ new friends.

2. These new students can speak _________, but they can't speak _________.

3. The boy talks with these new students _________.

4. These new students like to eat _________, for example, _________.

5. These new students usually _________ after school.
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单项选择题

分馏塔顶冷回流量变化，会引起（）质量的变化。

A、汽油

B、柴油

C、蜡油

D、液态烃
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