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第一章 绪论——科学试验及其误差控制

1.3试验误差

1、单选题：
‏观测、测定中，由于偶然因素如微气流、微小的温度变化、仪器的轻微振动等所引起的误差一般称为‌‏‌
选项：
A: 随机误差
B: 系统误差
C: 疏失误差
D: 可定误差
答案: 【 随机误差】点我阅读全文

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一、大学生身心健康概述与健康生活方式思考-1

大学生身心健康概述与健康生活方式思考-1单元测

1、单选题：
‌药物使用较为合理的是‎
选项：
A: 一定遵守医生嘱咐，并仔细阅读药物说明书并关注自身情况是否适合
B: 随意服用
C: 自己阅读说明书使用
D: 听取身边的朋友建议
答案: 【 一定遵守医生嘱咐，并仔细阅读药物说明书并关注自身情况是否适合】点我阅读全文

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hello微信小程序

测试1

1、单选题：
‍微信小程序是于何时正式发布?‎
选项：
A: 2016年6月
B: 2016年12
C: 2017年1月
D: 2017年6月
答案: 【 2017年1月】点我阅读全文

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1 c#概述

单元测试

1、单选题：
‏关于C#和.NET的关系描述错误的是(  )。‎
选项：
A: .NET是微软开发的一个硬件平台
B: C#是一个程序设计语言，运行在.net平台上用于创建应用程序
C: CLR是公共语言运行时，是提供内在管理，代码安全性检测等功能
D: Visual Studio是一个集成开发环境，可用于C#语言和.netFramework的交互
答案: 【 .NET是微软开发的一个硬件平台】点我阅读全文

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第2章 利率的决定理论

随堂检测

1、判断题：
‍利率由资本供给与资本需求在均衡条件下决定。‏
选项：
A: 正确
B: 错误
答案: 【 正确】点我阅读全文

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第一周 C54x DSP技术基础

C54x DSP技术基础_单元测试

1、单选题：
‎对于TMS320C54x系列DSP芯片，下列说法正确的是哪项？‏
选项：
A: 定点DSP
B: 专用DSP
C: 32位DSP
D: 浮点DSP
答案: 【 定点DSP】点我阅读全文

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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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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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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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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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