问题 问答题 简答题

高压静电电压表的原理是什么?

答案

参考答案:

在两个特定的电极间加电压u,电极间就会受到静电力f的作用,而且f的大小和u的数值有固定关系,因而测量f的大小或他引起的可动极板的位移或偏转就能确定所加电压u的大小。

阅读理解

阅读理解。

    For 99% of human history, people took their food from the world around them. They ate all that they

could find, and then moved on. Then around 10,000 years ago, about 1% of human history, people learned

to farm the land. 

    The kind of food we eat depends on which part of the world we live in, or which part of our country

we live in. For example, in the south of China they eat rice, but in the north they eat noodles. In European

countries near the sea, people eat a lot of fish. In central Europe, away from the sea, people don't eat so

much fish, but they eat more meat. For example, in Germany and Poland, there are hundreds of different

kinds of sausages.

    In North America, Australia, and Europe, people eat with knives and forks. In China, people eat with

chopsticks. In parts of India and the Middle East, people use their fingers to pick up food.

    Nowadays it is possible to transport food easily from one part of the world to another. We can eat

whatever we like, at any time of the year. In Britain, bananas come from Africa; rice comes from India or

the U.S.A.; strawberries come from Chile or Spain. Food is a very big business. But people in poor countries

are still hungry while people in rich countries eat too much.

1. 10,000 years ago, people ______. [ ]

A. learned to farm the land

B. cooked different kinds of food

C. couldn't find food around them

D. transported food from one country to another

2. In North America, Australia, and Europe, people ______.[ ]

A. eat with chopsticks

B. eat with knives and forks

C. use their fingers to pick up food

D. use bread to pick up food

3. ______ have many kinds of sausages. [ ]

A. Chile and Spain

B. America and Australia

C. China and Japan

D. Germany and Poland

4. Which of the following is NOT true? [ ]

A. What we eat depends on where we live.

B. Poor countries are still having food problems.

C. Rich countries don't need food from others.

D. Nowadays we can eat whatever we like at any time of the year.

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