mooc标签存档

走近微生物

走近微生物单元测验

1、单选题：
‏第一次利用显微镜观察到微生物的科学家是‏
选项：
A: 巴斯德
B: 贝林克
C: 弗来明
D: 吕文虎克
答案: 【 吕文虎克】点我阅读全文

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01导学概述篇

01-导学概述篇--单元测试

1、单选题：
操作系统的主要功能是管理计算机系统中的        。‍
选项：
A: 进程
B: 作业
C: 资源
D: 程序和数据
答案: 【 资源】点我阅读全文

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第2章仰望星空

第1周单元测试

1、单选题：
‌《天球运行论》一书是哪个科学家的伟大著作？‍
选项：
A: 布鲁诺
B: 哥白尼
C: 伽利略
D: 牛顿
答案: 【 哥白尼】点我阅读全文

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变压器

第2章 单元测验

1、单选题：
‍变压器空载电流小的原因是（   ）。‏
选项：
A: 一次绕组匝数多，电阻很大
B: 一次绕组的漏抗很大
C: 变压器的励磁阻抗很大
D: 变压器铁心的电阻很大
答案: 【 变压器的励磁阻抗很大】点我阅读全文

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第一章 财务导论

第一章

1、单选题：
‍人们在进行财务决策时必须考虑机会成本，其所依据的财务原则是（   ）。​
选项：
A: 比较优势原则
B: 自利行为原则
C: 行为原则
D: 资本市场效率原则
答案: 【 自利行为原则】点我阅读全文

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第一周中国法治建设的历程与启示上

第一周中国法治建设的历程与启示上

1、单选题：
‍新中国成立前夕颁布的具有临时宪法作用的是？‎
选项：
A: 《中华人民共和国宪法》
B: 《中华人民共和国土地改革法》
C: 《中国人民政治协商会议共同纲领》
D: 《中国人民政治协商会议组织法》
答案: 【 《中国人民政治协商会议共同纲领》】点我阅读全文

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Lesson2

Scanning

1、单选题：
‍Read the passage "The Discovery of X-rays" quickly and choose the paragraph(s) which contain(s) the answer(s). You may choose more than one answer for question 3. ​‍​The Discovery of X-rays​‍ ​Par. 1 Except for a brief description of the Compton effect, and a few other remarks, we have postponed the discussion of X-rays until the present chapter because it is particularly convenient to treat X-ray spectra after treating optical spectra. Although this ordering may have given the reader a distorted impression of the historical importance of X-rays, this impression will be corrected shortly as we describe the crucial role played by X-rays in the development of modern physics.​Par. 2 X-rays were discovered in 1895 by Roentgen while studying the phenomena of gaseous discharge. Using a cathode ray tube with a high voltage of several tens of kilovolts, he noticed that salts of barium would fluoresce when brought near the tube, although nothing visible was emitted by the tube. This effect persisted when the tube was wrapped with a layer of black cardboard. Roentgen soon established that the agency responsible for the fluorescence originated at the point at which the stream of energetic electrons struck the glass wall of the tube. Because of its unknown nature, he gave this agency the name X-rays. He found that X-rays could manifest themselves by darkening wrapped photographic plates, discharging charged electroscopes, as well as by causing fluorescence in a number of different substances. He also found that X-rays can penetrate considerable thicknesses of materials of low atomic number, whereas substances of high atomic number are relatively opaque. Roentgen took the first steps in identifying the nature of X-rays by using a system of slits to show that (1) they travel in straight lines, and that (2) they are uncharged, because they are not deflected by electric or magnetic fields.​Par. 3 The discovery of X-rays aroused the interest of all physicists, and many joined in the investigation of their properties. In 1899 Haga and Wind performed a single slit diffraction experiment with X-rays which showed that (3) X-rays are a wave motion phenomenon, and, from the size of the diffraction pattern, their wavelength could be estimated to be 10-8 cm. In 1906 Barkla proved that (4) the waves are transverse by showing that they can be polarized by scattering from many materials.​Par. 4 There is, of course, no longer anything unknown about the nature of X-rays. They are electromagnetic radiation of exactly the same nature as visible light, except that their wavelength is several orders of magnitude shorter. This conclusion follows from comparing properties 1 through 4 with the similar properties of visible light, but it was actually postulated by Thomson several years before all these properties were known. Thomson argued that X-rays are electromagnetic radiation because such radiation would be expected to be emitted from the point at which the electrons strike the wall of a cathode ray tube. At this point, the electrons suffer very violent accelerations in coming to a stop and, according to classical electromagnetic theory, all accelerated charged particles emit electromagnetic radiations. We shall see later that this explanation of the production of X-rays is at least partially correct.​Par. 5 In common with other electromagnetic radiations, X-rays exhibit particle-like aspects as well as wave-like aspects. The reader will recall that the Compton effect, which is one of the most convincing demonstrations of the existence of quanta, was originally observed with electromagnetic radiation in the X-ray region of wavelengths.​‍​‍When were X-rays discovered?​
选项：
A: Par. 1
B: Par. 2
C: Par. 3
D: Par. 4
E: Par. 5
答案: 【 Par. 2】点我阅读全文

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第一章肌肉活动

第一章肌肉活动

1、单选题：
组成肌肉的基本单位是（ ）。​​‎​
选项：
A: 肌腹
B: 最小肌肉群
C: 肌纤维
D: 肌腱
答案: 【 肌纤维】点我阅读全文

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第1章 工程经济与项目管理概论

第1单元测试

1、单选题：
‎建设工程项目管理中的费用目标对施工方而言是（ ）。 ‏
选项：
A: 投资目标
B: 成本目标
C: 概算目标 
D: 预算目标 
答案: 【 成本目标】点我阅读全文

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第一单元导论

随堂测试2导论

1、单选题：
‍亚当.斯密认为的“看不见的手”指的是（     ）‍
选项：
A: 政府
B: 资本家
C: 消费者
D: 市场
答案: 【 市场】点我阅读全文

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