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问题 选择题

如图所示的电路中，当a、b端加直流电压时，灯发光，灯不亮，当加同样电压的交流电源时，发光但较暗，灯发光较亮，那么以下正确的是（ ）

A．A中接的是电感线圈，B中接的是电容器

B．A中接的是电容器，B中接的是电感线圈

C．A中接的是电阻，B中接的是电容器

D．若加的交流电频率增大，电压不变，则灯变得更暗，灯变得更亮

答案

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 电感的特点是"通直流、阻交流，通低频、阻高频"。电容的特点是："通交流、隔直流，通高频、阻低频"。由题意：a、b两端加直流电压时，灯不亮；加交流电压时，较亮，可知B为电容器，而灯先是亮的，后又较暗，可知A为电感线圈。交流电频率越大时，线圈感抗越大，电容器容抗越小，故D为正确。应选A、D。

单项选择题

In the last decade the mass media have grown worldwide to be larger, more influential and more powerful. After it was possible in the Federal Republic of Germany in the 60s to receive one TV program and in the 60s and 70s to receive three TV programs, the number of receivable TV programs has risen for a huge part of the population in western Europe through cable TV to eleven or even more programs in the last years. More TV channels are announced. Additionally there is the huge offer of videos. The distribution of video recorders in the population is increasing. Worldwide we are on the way to communication to a mass media society in which fiction, fantasy, the definition of reality assumes a greater role than reality itself, where people want to be permanently entertained, and where the description of the content gains more emphasis than the content itself.

For centuries news on crime have greatly attracted the population, In the Middle Ages ballad singers moved very successfully from town to town in order to spread their ballads which were to a great part murder stories. Criminal stories are not a new development because they do not report anything really new. They are regularly told according to the pattern of the "familiar sensation" because they have a function of relief for the society, because through them, the "law-abiding citizen" can set himself apart from the criminal, because they prove to him that his behavior is "normal" and because he can be content to feel that he is better than the criminals and that he successfully managed to escape the criminal act. There is a huge demand in the population for crime news because they are entertaining and remove the boredom of everyday life. The mass media willingly fulfill this demand because crime news are cheap and easy to get hold of and because they help sell almost any product. That is why there is a symbiosis, an unholy alliance between mass media and society against which the critical criminologist advances his objections almost in vain.

Which of the following could most probably be discussed before this passage().

A. Mass media.

B. Criminal stories.

C. The invention of TV.

D. TV programs in Germany.
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单项选择题

芙蓉鱼片在添加鸡蛋时应将打发的鸡蛋清分（）加入。

A.一次

B.两次

C.三次

D.五次
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