mooc答案类别订阅

第1单元测验-信息技术与计算机

1、单选题：
​计算思维是运用计算机科学的(   )进行问题求解、系统设计、以及人类行为理解等涵盖计算机科学之广度的一系列思维活动。‍
选项：
A: 基础概念
B: 思维方式
C: 程序设计原理
D: 操作系统原理
答案: 【 基础概念】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

6.1 What is a Cause and Effect Essay随堂测验

1、单选题：
‌How can we organize the cause and effect essay?‌
选项：
A: Through chronological order.
B: Through order of importance.
C: Through categorical order.
D: All of them
答案: 【 All of them】点我阅读全文

发射机组成

1、单选题：
‍调制应用在通信系统的（ ）​
选项：
A: 发送设备
B: 接收设备
C: 发送设备和接收设备
D: 以上都不对
答案: 【 发送设备】点我阅读全文

1.1随堂测验

1、单选题：
‎RRB粒度分布方程中的n是           。​
选项：
A: 功指数        
B: 旋涡指数 
C: 均匀性指数
D: 时间指数
答案: 【 均匀性指数】点我阅读全文

AchievementTest

UnitEight

普通话及语音基本知识单元测验

1、单选题：
‏普通话以（      ）最为基础方言。‎
选项：
A: 北京方言
B: 北方方言
C: 吴方言
D: 湘方言
答案: 【 北方方言】点我阅读全文

10-1-1微分方程的概念随堂测试

1、单选题：

‎

‎选项：
A:
B:
C:
D:
答案: 【 】点我阅读全文

第一章单元测试

1、单选题：
‍行政一词最早源于（     ）‌‍‌
选项：
A: 英文
B: 拉丁文
C: 中文
D: 法文
答案: 【 拉丁文】点我阅读全文

01 绪论单元测试

1、单选题：
‎对太阳辐射平均反射率最小的圈层物质是？‏
选项：
A: 大气
B: 海洋
C: 岩石
D: 森林
E: 冰雪
答案: 【 海洋】点我阅读全文