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光电显示技术测验（二）

1、填空题：
‍黑白显像管的基本结构包括（）、偏转系统、荧光屏和玻壳。‎
答案: 【 电子枪】点我阅读全文

QuizzesDrugQualityStandardandQualityControl

1、单选题：
‍The principle of English names for drugs in Chinese Pharmacopoeia follows（ ） formulated by the World Health Organization.‏‍‏
选项：
A: ChP
B: CADN
C: INN
D: BNF
答案: 【 INN】点我阅读全文

单元测试一

1、单选题：
‌船舶电力系统是由_____ 组成的。‏‌‏‌‏
选项：
A: 主电源、应急电源、电网、负载
B: 电源设备、调压器、电力网
C: 电源设备、负载    
D: 电源设备、配电装置、电力网、负载
答案: 【 电源设备、配电装置、电力网、负载】点我阅读全文

随机事件与概率1单元测验

1、单选题：

​

​选项：
A:
B:
C:
D:
答案: 【 】点我阅读全文

第一章测试

1、单选题：
‏关于BIM技术，说法正确的是​
选项：
A: BIM技术是一个软件
B: BIM技术就是建立三维模型
C: BIM技术各专业数据保存在各专业模型中，不能流通
D: BIM在建设工程及设计全生命期内，对其物理和功能特性进行数字化表达，并以此设计、施工、运营的过程和结果的总称。
答案: 【 BIM在建设工程及设计全生命期内，对其物理和功能特性进行数字化表达，并以此设计、施工、运营的过程和结果的总称。】点我阅读全文

妆前皮肤护理

1、单选题：
‏敏感性皮肤应先用( )的基础隔离，再施涂乳液。‍‏‍
选项：
A: 清洁化妆水  
B: 抗敏化妆 
C: 营养化妆水
D: 收敛化妆水
答案: 【 抗敏化妆  】点我阅读全文

单元测试

1、单选题：
​我国果树大概有（    ）科‏​‏
选项：
A: 20
B: 30
C: 40
D: 50
答案: 【 50】点我阅读全文

第一章做一个素质全面的创业者单元测验

1、单选题：
​创业团队领袖又可以称为（   ）‍
选项：
A: 控股股东
B: 卓越管理者
C: 法定代表人
D: 创业企业家
答案: 【 创业企业家】点我阅读全文

第1周测验

1、单选题：
​经济学中的“稀缺性”是指（      ）​
选项：
A: 世界上大多数人生活在贫困中
B: 相对于资源的需求而言，资源总是不足的
C: 利用资源必须考虑下一代
D: 地球上的资源终将被人类消耗光
答案: 【 相对于资源的需求而言，资源总是不足的】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