慕课标签存档

1 模块一学习准备

1.2 随堂测试

1、多选题：
‌不同的学者对教学设计有不同的界定,但他们也都有共同地方,可归纳为三个关键词,即 ​
选项：
A: “理论”
B: “系统”
C: “优化”
D: “生成"
答案: 【 “理论”;
“系统”;
“优化” 】点我阅读全文

本文共有 174 人阅读

Unit 1 Job Interview

Quiz for Unit 1

1、单选题：
‌You’d better finish your self-introduction within _________.‏
选项：
A: 1 to 2 minutes 
B: 3 to 5 minutes
C: 5 to 7 minutes   
D: 7 to 10 minutes
答案: 【 3 to 5 minutes】点我阅读全文

本文共有 98 人阅读

第一讲绪论

第一讲绪论

1、单选题：
‍分子内的运动中，只有      不会产生光谱。‏
选项：
A: 转动
B: 平动
C: 核的自旋跃迁
D: 电子跃迁
答案: 【 平动】点我阅读全文

本文共有 100 人阅读

Chapter 1 Comprehensive Listening Skills and Listening Competence

5 questions about listening process

1、单选题：
‍what knowledge do we use in ‘bottom-up’ process ?‌
选项：
A: prior knowledge
B: linguistic knowledge
C: --
D: --
答案: 【 linguistic knowledge】点我阅读全文

本文共有 115 人阅读

园林工程总平面图及局部详图设计

局部详图设计随堂测验

1、单选题：
‏局部平面一般为多大图幅‍
选项：
A: A0
B: A1
C: A2
D: A3
答案: 【 A2】点我阅读全文

本文共有 97 人阅读

1 液压传动基础

单元测试1

1、判断题：
‏液压油的粘度随着温度的升高而降低。‌
选项：
A: 正确
B: 错误
答案: 【 正确】点我阅读全文

本文共有 119 人阅读

第一章 商周时期家具

第一章单元测验

1、单选题：
​构图形式一般有镜像的或者二方连续两种形式的纹样是​
选项：
A: 窃曲纹
B: 凤纹
C: 饕餮纹
D: 虎纹
答案: 【 窃曲纹】点我阅读全文

本文共有 210 人阅读

第一章基础营养学

基础营养学测试

1、单选题：
维生素D的功能包括：‌‍‌
选项：
A: 促进成骨细胞钙盐沉积
B: 促进肾小管对钙、磷的重吸收
C: 抑制破骨细胞的作用
D: 促进小肠对钙的吸收
答案: 【 促进成骨细胞钙盐沉积】点我阅读全文

本文共有 108 人阅读

第一节运动健身的健康效益

运动健身的健康效益

1、多选题：
‌健康“五快”的标准有快食、快眠、快便‌
选项：
A: 快语
B: 快行
C: 快跑
D: 快记
答案: 【 快语;
快行】点我阅读全文

本文共有 115 人阅读

Lesson 2

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

本文共有 80 人阅读