凸轮机构是是一种常见的低副机构。

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问题:

凸轮机构是是一种常见的低副机构。

考点:机械维修工考试机械维修工考试题库
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生物分类的基本单位是______;除病毒外,生物体结构和功能基本单位是______,生物体的组织,是在细胞分裂的基础上,经过细胞______形成的.

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非正弦周期信号的谐波分量表达式如何表示?式中每一项的意义是什么?

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Passage Four

Adam Smith was the founder of economics as a distinct field of study. He wrote only one book on the subject — The Wealth of Nations, published in 1776. Smith was 53 years old at the time. His friend David Hume found the book such hard going that he doubted many people would read it. But Hume was wrong — people have been reading it for more than 200 years now.
The Wealth of Nations, in Smith’s view, was the result not of accumulating gold or silver, as many of that time believed, but of ordinary people working and trading in free markets. To Smith, the remarkable thing about the wealth produced by a market economy is that it does not result from any organized plan, rather, it is the unintended outcome of the actions of many people, each of whom is pursuing the incentives the market offers with his or her own interests in mind.
"It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest, every individual is continually exerting himself to find out the most advantageous employment for whatever capital he can command. By directing that industry in such a manner as its produce may be of the greatest value, he intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was a part of his intention".
Much of the discipline of economics as it has developed over two centuries consists of elaboration of ideas found in Smith’s work. The idea of the "invisible hand" of market incentives that channels people’s efforts in directions that are beneficial to their neighbors remains one of the most durable of Smith’s contributions.

It can be inferred from Para. I that ______.

A.what Hume doubted the Wealth of Nation was proved wrong

B.before Adam Smith, there was no economics

C.the Wealth of Nations is popular now

D.all of the above

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祛风湿药的主要功效是( )

A.祛除风湿,知血止痛

B.祛除风湿,活血消肿

C.祛除风湿,舒筋活络

D.祛除风湿,强壮筋骨

E.祛除风湿,解除痹痛

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工件使用大平面定位时,必须把定位平面做成微凸形。( )

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