mooc答案类别订阅

第一单元测试

1、单选题：
‌设A、B、C为三个随机事件，则事件“至少有两个发生”可表述为（  ）.‌
选项：
A:
B:
C:
D:
答案: 【 】点我阅读全文

第一周测试

1、单选题：

‍

‌

‍选项：
A: 8
B: -12
C: 24
D: -4
答案: 【 -4】点我阅读全文

单元测验

1、单选题：
‎进化论是由_________提出的。‏
选项：
A: 达尔文
B: 瓦维洛夫
C: 孟德尔
D: 约翰逊
答案: 【 达尔文】点我阅读全文

1.1.1二、三阶行列式(随堂测验

1、单选题：

‍

‌选项：
A:
B:
C:
D:
答案: 【 】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

第一单元测验

1、单选题：
‎《共产党宣言》发表于哪一年？​
选项：
A: 1848
B: 1850
C: 1852
D: 1854
答案: 【 1848】点我阅读全文

《第一章 世界的物质性及发展规律（二）》单元测试题

1、单选题：
‎唯物辩证法认为发展的实质是（     ）‏
选项：
A: 事物数量的增加或减少  
B: 事物的简单重复和循环   
C: 新事物的产生和旧事物的灭亡   
D: 事物空间的变化   
答案: 【 新事物的产生和旧事物的灭亡   】点我阅读全文

任意球、罚球点球、掷界外球单元测试

1、单选题：
​任意球可分为几种 ？‎
选项：
A: 直接任意球和间接任意球两种
B: 直接任意球和球点球
C: 间接任意球和球点球
D: 直接任意球、间接任意球和球点球
答案: 【 直接任意球和间接任意球两种】点我阅读全文

Quiz for Lecture 2

1、填空题：
Read the list of common organic chemicals below and try to put them in the right categories. Write its number in the right place. ‌shampoo‌gasoline‌perfume‌drug‌paint‌plastic‌paper‌fertilizer‌wood‌coal‌cleaning solvent‌vitamin‌soap‌natural gas‌moth ball‌insect repellent‌nail polish remover‌‌Category 1  insectifuge _____________________. ‌‌‌‌‌
答案: 【 15##%_YZPRLFH_%##16】点我阅读全文

第一章单元测验

1、单选题：
‍泛耐药菌是指：​
选项：
A: 对任一一种抗菌药物耐药的细菌
B: 对两种或两种以上抗菌药物耐药的细菌
C: 对三种或三种以上抗菌药物耐药的细菌
D: 对五种或五种以上抗菌药物耐药的细菌
答案: 【 对五种或五种以上抗菌药物耐药的细菌】点我阅读全文