试题与答案

在水平向右的匀强磁场中,一线框绕垂直于磁感线的轴匀速转动,线框通过电刷、圆环、导

题型:选择题

题目:

在水平向右的匀强磁场中,一线框绕垂直于磁感线的轴匀速转动,线框通过电刷、圆环、导线等与定值电阻组成闭合回路。t1t2时刻线圈分别转到图(a)、(b)所示的位置,下列说法中正确的是

[ ]

A.t1时刻电阻中的电流最大,方向从左向右

B.t1时刻电阻中的电流最大,方向从右向左

C.t2时刻电阻中的电流最大,方向从左向右

D.t2时刻电阻中的电流最大,方向从右向左

答案:

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参考答案:回忆说:柏拉图认为,人生来就具有一种基本上在发展过程中展现并成为有意识的先天知识(理念)。后天环境对人不具影响,一切研究、学习都只不过是对先天理念的“回忆”。

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题型:阅读理解

阅读理解。

     Why do plants grow in some places and not in others? Why does some land have so much growing on it,

while other land has almost no plants growing on it at all.

     To grow, plants need several things. One is warmth. In very cold places almost nothing grows. Plants also

need water. In very dry parts of the Earth only a few unusual plants can grow. That's why dry deserts

everywhere are almost not covered by trees or grass.

     Plants must also have a place in which to put down their roots and grow. They find it difficult to grow on

hard land. The town is built on hard land. The plants here can only grow in the soil between the cracks (缝隙)

of the stones.

     Another thing plants must have before they can grow is food.

     What will happen if we try to make things grow on the sandy beach? A few plants, such as beach grass,

will grow in sand, but most plants won't. Even if the weather is warm enough and we water the plants each

day, many of them will die because the sand on this beach has almost no food for plants.

1. Plants can grow ______. [ ]

A. nowhere

B. somewhere

C. anywhere

D. everywhere

2. The passage tells us that plants need            things to grow. [ ]

A. two

B. three

C. four

D. five

3. Plants like to grow in            soil. [ ]

A. dry

B. hard

C. soft

D. hot

4. From the passage, we can know most of the plants aren't able to grow on the sandy beach

    because ______. [ ]

A. the soil is too poor

B. there is too much water

C. sunshine is not enough

D. sunlight is too strong

5. Maybe the passage can be found in a _____ book. [ ]

A. travel

B. history

C. physics

D. science

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