慕课标签存档订阅

随堂练习

1、单选题：
‎随堂练习： 中国现存的最早的雕版印刷插画作品是哪一件作品？‍
选项：
A: 水浒叶子
B: 金刚般若经
C: 陀罗尼经咒图
D: 《大藏经》
答案: 【 金刚般若经】点我阅读全文

交换概论测试题

1、单选题：
‌采用电路交换方式的网络适于支持的业务是：‌
选项：
A: 实时可变速率的业务
B: 实时恒定速率的业务
C: 高可靠可变速率的业务
D: 高可靠恒定速率的业务
答案: 【 实时恒定速率的业务】点我阅读全文

第1章单元测验

1、单选题：
​在国际连锁业协会以及西方各国政府的规定中，往往把经营（）家以上商店的零售业或者饮食业组织称为连锁商店。‏​‏
选项：
A: 9
B: 15
C: 11
D: 20
答案: 【 11】点我阅读全文

第二讲 单元测验

1、单选题：
‍‎‍下列选项中不属于工具型角色的是（     ）‎
选项：
A: 独立
B: 支配性
C: 仁慈
D: 果断
答案: 【 仁慈】点我阅读全文

知识点1.1微波波段的划分及特点

1、单选题：
‎微波的频率范围是​‎​
选项：
A: 30MHz~300MHz   
B: 300MHz~3000MHz 
C: 30GHz~3000GHz  
D: 300MHz~3000GHz 
答案: 【 300MHz~3000GHz 】点我阅读全文

第一周 单元测验

1、单选题：
1.下列选项中对保健食品描述正确的是：​
选项：
A: 保健食品可代替药物。
B: 保健食品的标签、说明书可涉及疾病预防、治疗功能。
C: 列入保健食品原料目录的原料可用于其他食品生产。
D: 保健食品声称保健功能，应当具有科学依据，不得对人体产生急性、亚急性或者慢性危害。
答案: 【 保健食品声称保健功能，应当具有科学依据，不得对人体产生急性、亚急性或者慢性危害。】点我阅读全文

1-10随堂测验

1、多选题：
​连续单向板中的构造钢筋包括（）。‍
选项：
A: 跨主梁承受负弯矩的钢筋
B: 分布筋
C: 连续单向板支承于墙体时的构造钢筋 
D:  板底受拉钢筋 
答案: 【 跨主梁承受负弯矩的钢筋;
分布筋;
连续单向板支承于墙体时的构造钢筋 】点我阅读全文

第一章 保险概述测试题

1、单选题：
‍在保险期间，以下通常不属于保险事故的是（  ）。‎
选项：
A: 暴雨灾害
B: 爆炸
C: 通货膨胀
D: 意外火灾
答案: 【 通货膨胀】点我阅读全文

位矢 位移 速度和加速度的直角坐标表示--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