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1.1.4测测你对思维导图的认识

1、判断题：
‏思维导图可以将人们的思维过程和思考结果可视化。‏
选项：
A: 正确
B: 错误
答案: 【 正确】点我阅读全文

第7周随堂测验

1、判断题：
‌十足目是甲壳动物中最大的一个目，包括有近万余种的甲壳动物。‎
选项：
A: 正确
B: 错误
答案: 【 正确】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1章 单元测验

1、单选题：
‌n = 3、l = 2 时，m可取的数值有‍
选项：
A: 5个
B: 1个
C: 2个
D: 3个
E: 4个
F: 6个
G: 7个
答案: 【 5个】点我阅读全文

Chapter1State-SpaceDescriptionofControlSystems

1、填空题：

‎

‍答案: 【 根据具体状态变量而定】点我阅读全文

专题一单元测验

1、单选题：
 （  ）1、公共管理学是一门以            和国家治理的实践作为研究对象的学问。   ‍‌‍
选项：
A: 私人事务管理
B: 公共事务管理
C: 所有事务管理
D: 跨国事务管理
答案: 【 公共事务管理】点我阅读全文

前四讲 单元测试

1、单选题：
​图坦卡蒙面具是哪个文化的艺术品？‎
选项：
A: 古埃及
B: 古希腊
C: 古罗马
D: 古巴比伦
答案: 【 古埃及】点我阅读全文

正常分娩测试

1、单选题：
‍正常分娩时最主要的产力是​
选项：
A: 子宫收缩力
B: 骨骼收缩力
C: 肛提肌收缩力
D: 膈肌收缩力
答案: 【 子宫收缩力】点我阅读全文

单元测试

1、单选题：
‏资料的搜集应在论文写作的‌
选项：
A: 开始写作前
B: 写作过程中
C: 综述写作时
D: 贯穿全过程
答案: 【 贯穿全过程】点我阅读全文

单元测验

1、单选题：
‍下列关于旅游资源内涵的叙述，正确的是‏
选项：
A: 旅游资源是指具有一定吸引力，能使旅游者得到物质享受和精神满足的各种事物和因素
B: 旅游资源是指对旅游者产生吸引力，可以为旅游业开发利用，并产生经济效益和社会效益的各种事物和因素
C: 具有一定的经济、社会和文化价值，给旅游业带来一定经济效益和社会效益的各种因素都是旅游资源
D: 凡能达到观光、猎奇、探险、疗养等旅游目的的一切自然资源和文化资源都是旅游资源
答案: 【 旅游资源是指对旅游者产生吸引力，可以为旅游业开发利用，并产生经济效益和社会效益的各种事物和因素】点我阅读全文