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问题 填空题

一台家用电视机待机状态下的电功率大约是10W，这表示1秒钟电流做的功是______．如果这台电视机平均每天的待机时间以18h计，那么在待机状态下100天消耗的电能是______kW•h．

答案

（1）1s电流做的功W=10W×1s=10J；

（2）电视机平均每天的待机时间以18h计，

那么在待机状态下100天消耗的电能

W′=Pt′=0.01kW×18h×100=18kW•h；

故答案为：10J；18．

单项选择题

B


Waste can be seen everywhere in the school. Some students ask for more food than they can eat and others often forget to turn off the lights when they leave the classroom. They say they can afford these things. But I don’t agree with them.
Waste can bring a lot of problems. Although China is rich in some resources (资源), we are short of(缺乏) others, for example, fresh water(淡水). It is reported that we will have no coal (煤) or oil to use in 100 years. So if we go on wasting our resources, what can we use in the future and where can we move Think about it. I think we should say no to the students who waste things every day. Everybody should stop wasting as soon as possible.
In our everyday life, we can do many things to prevent waste from happening, for example, turn off the water taps (水龙头) when we finish washing, turn off the lights when we leave the classroom, try not to order more food than we need, and so on. Little by little, everything will he changed. Waste can be stopped one day, if we do our best.

Which of the following is right ( )

A．Waste brings problems.

B．Waste can bring no problem.

C．China is rich in fresh water.

D．Students never waste things.
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单项选择题

某药品批号为970612（同生产日期），其有效期为2年，该药品可使用至

A．1999年6月11日
B．1999年6月12日
C．1999年5月11日
D．1999年6月30日
E．1999年7月1日
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