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问题 问答题

如图所示，是四种常见家用电器的电路图，请选择正确序号填写在家用电器名称后面．电饭锅______，双缸洗衣机______，调光台灯______，电冰箱______．

答案

①电饭锅是利用电流的热效应工作的，由选项可知C符合；

②双缸洗衣机可以分别进行洗衣和脱水，由选项可知A符合；

③调光台灯是通过滑动变阻器调节接入电路中的电阻，从而改变灯泡两端的电压和通过的电流，达到调节灯泡亮暗，由选项可知D符合；

④电冰箱中照明灯是由门控开关控制、电动机是由温控开关控制的，两者为并联，由选项可知B符合．

故答案为：C；A；D；B．

单项选择题

The human nose is an underrated tool. Humans are often thought to be insensitive smellers compared with animals, (51) this is largely because, unlike animals, we stand upright. This means that our noses are (52) to perceiving those smells which float through the air, missing the majority of smells which stick to surfaces. In fact, (53) , we are extremely sensitive to smells, even if we do not generally realize it. Our noses are capable of (54) human smells when these are diluted to far below one part in one million.

Strangely, some people find that they can smell one type of flower but not another, (55) others are sensitive to the smells of both flowers. This may be because some people do not have the genes necessary to generate (56) smell receptors in the nose. These receptors are the cells which sense smells and send (57) to the brain. However, it has been found that even people insensitive to a certain smell at first can suddenly become sensitive to it when (58) to it often enough.

The explanation for insensitivity to smell seems to be that the brain finds it (59) to keep all smell receptors working all the time but can (60) new receptors if necessary.

51().

A.although 

B.as 

C.but 

D.while
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单项选择题

在操作系统中，可以并行工作的基本单位是______。

A．作业

B．函数

C．进程

D．过程
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