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问题 选择题

如下图是甲、乙两个电阻的电流I与电压U的关系图象，将它们并连接入电路，下列说法正确的是（　　）

A．通过甲的电流大于通过乙的电流

B．通过甲的电流小于通过乙的电流

C．甲、乙并联的总电阻随它们两端电压的升高而减小

D．甲、乙并联的总电阻随它们两端电压的升高而增大

答案

答案：D

（1）由I﹣U图象可知：当电压较小，两电阻两端电压相等时，流过甲电阻的电流大于流过乙电阻的电流，当电压较大时，通过甲电阻的电流小于通过乙的电流；由此可见两电阻并联时，电压较小时通过甲的电流大于通过乙的电流，电压较大时通过甲电阻的电流小于乙电阻的电流，故AB错误；

（2）由图象知，乙电阻不随电压的变化而变化，是一个定值；甲电阻阻值随电压的增大而变大，由并联电路的电阻特点知，随电阻阻值的增大，并联电阻阻值变大，所以甲、乙并联的总电阻随它们两端电压的升高而增大，故C错误，D正确；

故选D．

阅读理解

What does blood do for us? It brings food to all parts of our bodies and takes waste away from them. All parts of our bodies are made of cells. These cells are very small. They all need all the time. No one could make pictures of cells because no one could see them.

What makes the blood move round the body? The heart is a pump. It pumps the blood and sends it round the body. The heart has rooms with doors between them. It pumps blood in and out through these doors by changing the size of the rooms so that the doors are opened and shut. The heart keeps a stream of blood going all around the body and back again to itself. The heart is a very important part of one's body. When it stops beating, one will die.

小题1:Blood is important to our body because it can         

A．provide pictures of cells

B．bring food and waste

C．from a stream

D．move around the heart小题2:What does the underline word "microscope" mean in Chinese?

A．显微镜

B．探测仪

C．放大镜

D．摄像机小题3:According to the passage, a pump is used to         

A．open or shut doors

B．send something up

C．change the size of rooms

D．make something in or out
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单项选择题

SWOT分析法中，WO战略是（）。

A、增长性战略

B、扭转型战略

C、多种经营战略

D、防御型战略
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