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第二章 水质分析质量保障体系

单元测验

1、单选题：
对某试样进行平行三次测定，得 CaO 平均含量为 30.6% ，而真实含水量为 30.3% ，则 30.6%-30.3%=0.3% 为（）‏‌‏
选项：
A: 相对误差
B: 相对偏差
C: 绝对误差
D: 绝对偏差
答案: 【 绝对误差】点我阅读全文

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来自大自然的纤维

来自大自然的纤维单元测验

1、单选题：
‏细绒棉又称为‌
选项：
A: 海岛棉
B: 陆地棉
C: 亚洲棉
D: 非洲棉
答案: 【 陆地棉】点我阅读全文

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第1周 绪论

1.1 魔鬼还是天使-王者农药随堂测验

1、单选题：
​杀虫剂、杀菌剂、除草剂是按照农药的        来分类的。​
选项：
A: 作用对象
B: 原料来源
C: 作用机理
D: 组成成分
答案: 【 作用对象】点我阅读全文

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Lesson2

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

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第一章 绪论——社会心理学何为？

第一章 单元测试

1、单选题：
‎社会生活中，（）是一种驱动人类思想和行为的巨大力量，当我们置身于某种情境时，似乎被某种魔力所控制，常常会变得身不由己。‏‎‏
选项：
A: 关系
B: 结构
C: 情境
D: 互动
答案: 【 情境】点我阅读全文

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第一章组织与人力资源管理概论

第一章单元测验

1、单选题：
​通常所说的“人才资源是第一资源”“企业的竞争往往是人才的竞争”等观点是体现了人力资源什么特征？​
选项：
A: 一种可再生的生物性资源
B: 在经济活动中是居于主导地位的能动性资源
C: 具有时效性的资源
D: 具有动态性的资源
答案: 【 在经济活动中是居于主导地位的能动性资源】点我阅读全文

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第十章碱金属和碱土金属元素

第九章、第十章单元测试

1、单选题：
 在下列各种酸中酸性最强的是______。‌‏‌
选项：
A: H2SO4  
B: H3PO4  
C: HClO4    
D: H3AsO4
答案: 【 HClO4    】点我阅读全文

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第一章 宋辽金时期社会文化与文学发展概况

第一章测试

1、单选题：
‌陈寅恪在《邓广铭宋史职官志考证序》中指出：“华夏民族之文化，历数千载之演进，造极于     之世。”‍‌‍
选项：
A: 前汉
B: 李唐
C: 赵宋
D: 朱明
答案: 【 赵宋】点我阅读全文

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第一周第一章国际贸易实务总论

第一章单元测验

1、单选题：
​学习《国际贸易实务》课程的任务有(   )‏
选项：
A: 参加国际贸易会议
B: 掌握进出口贸易操作技能
C: 提高外语沟通能力
D: 学习如何经营跨境电商
答案: 【 掌握进出口贸易操作技能】点我阅读全文

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第二章信息安全法律法规（必修）

第二章测试

1、判断题：
​刑事法律关系，用于解决有关部门依法行政、依法管理网络的问题（）‍
选项：
A: 正确
B: 错误
答案: 【 错误】点我阅读全文

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