mooc答案类别订阅

第一章 章节测试

1、单选题：
‎食品加工过程中，属于人为故意加入的化学性危害‎
选项：
A: 石子、木块
B: 食品添加剂
C: 食品加工过程中的清洁剂等
D: 全部都是
答案: 【 食品添加剂】点我阅读全文

第一周单元测验

1、单选题：
​经常账户各项目都是按（）记录。‏​‏​‏
选项：
A: 总额
B: 差额
C: 净额
D: 余额
答案: 【 总额】点我阅读全文

1.4Quiz

1、判断题：
‎The author thinks that students' language deficits should be blamed on schools because the schools never teach grammar.‏
选项：
A: 正确
B: 错误
答案: 【 错误】点我阅读全文

概说广播节目播音与主持 单元测试

1、单选题：
“破立统一的无我之境”中“无我”指的是什么？‍‍
选项：
A: 一切为内容服务
B: 要时刻在节目中强调播音员的声音、形象及流畅的表达
C: 播音员要在节目中完全忘却自我身份
D: 播音员在节目中要时刻为受众着想
答案: 【 一切为内容服务】点我阅读全文

单元测验

1、单选题：
请根据研究问题操作化的步骤将下列表述进行排序。​（1）将研究问题转化为变量间关系，将概念转化为变量​（2）将抽象问题转化为具体问题，将指称边界不明确的要素具体化为边界清楚的要素​（3）明确自己研究的目的是描述性的、判断性的，还是解释性的​‍（4）澄清要研究的问题，明确问题中的每一个要素​
选项：
A: （2）（1）（3）（4）
B: （3）（2）（4）（1）
C: （3）（4）（2）（1）
D: （2）（1）（4）（3）
答案: 【 （3）（4）（2）（1）】点我阅读全文

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

第一章质点运动学单元测验

1、单选题：

​一运动质点在某瞬时位于矢径的端点处, 其速度大小为

​选项：
A:   
B:     
C:      
D:   
答案: 【   】点我阅读全文

第一讲测试

1、单选题：
‏第一代计算机的主要部件是由______构成的。‏
选项：
A: 电子管
B: 晶体管
C: 中小规模集成电路
D: 大规模集成电路
答案: 【 电子管】点我阅读全文

冲裁变形过程及断面特征随堂测验

1、单选题：
‍冲裁是利用模具使板料沿着一定的轮廓曲线产生（  ）的一种冲压工序。‌
选项：
A: 分离
B: 成形
C: 变形
D: 以上都不是
答案: 【 分离】点我阅读全文

第二章

1、单选题：
‍大爆炸之后50万年的宇宙和现在的临近宇宙，气体（氢）分别是以什么形式存在的？‌
选项：
A: 中性，中性
B: 中性，电离
C: 电离，电离
D: 电离，中性
答案: 【 中性，电离】点我阅读全文