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问题 选择题

下列关于催化剂的说法不正确的是（  ）

A．任何化学反应都需要催化剂

B．催化剂可以提高某些化学反应的速率

C．催化剂可以降低某些化学反应的速率

D．化学反应前后，催化剂的质量和化学性质都不变

答案

答案：A

题目分析：A、不是所有化学反应都需要催化剂，不使用催化剂物质也能发生化学反应，如碳在空气中燃烧就不需要催化剂，故A错误．

B、催化剂能够改变化学反应速率，既可加快反应速率，也可以减慢反应速率，故B正确．

C、催化剂能够改变化学反应速率，既可加快反应速率，也可以减慢反应速率，故C正确．

D、由催化剂的概念可知，化学反应前后，催化剂的质量和化学性质都不变，故D正确．

故答案为：A．

点评：本题难度不大，考查了对催化剂概念的理解，把握催化剂的特点是正确解答催化剂问题的关键．

阅读理解

Dereck Joubert and his wife, Beverly, have made many films about wild animals in Africa. Their films and photographs are very popular and one of the photographs has been on the front cover of a National Geographic magazine.

　　A working day foe Dereck and Beverly starts very early-at 4:30 in the morning! That's when they get up and start filming. And it's a long day-they often work until 8:30 in the evening. In the winter it's very cold and in the summer it can be 40℃. Dereck always does the filming-Beverly never does that, and she doesn't write. But Dereck never takes photographs or records the sound. They work very well as a team, and they both believe we should shoot animals with cameras-not with guns!

　　When they have finished filming and taking photographs for the day, they have dinner and Dereck usually writes while Beverly looks at her photographs. At night, they usually sleep in a small tent, but they sometimes sleep in the Land Cruiser-when you're very close to wild animals, it's sometimes safer to sleep in the car.

　　Dereck and Beverly have also traveled around the world and given talks about their work. Dereck says that animals are not just something to look at-they play an important role. Beverly thinks the wild animals can teach us a lot about ourselves.

小题1: Dereck and Beverly start working ______.

A．at 4:30 in the morning

B．at 4:30 in the afternoon

C．at 8:30 in the morning

D．at 8:30 in the evening小题2: Dereck and Beverly usually sleep ______ at night.

A．in a car

B．in a tent

C．in a house

D．in a hotel小题3: Beverly thinks the wild animals ______.

A．are something to look at

B．are very popular

C．play an unimportant role

D．can teach us a lot
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问答题

你认为中学化学教学中，一节好课的标准是什么
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