mooc答案类别

第1章丝绸历史与文化

随堂测验

1、单选题：
《雍正像耕织图册》分为（ ）和（ ）两部分。‌‏‌
选项：
A: 织图、练图
B: 织图、染图
C: 耕图、染图
D: 耕图、织图 
答案: 【 耕图、织图  】点我阅读全文

本文共有 98 人阅读

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

本文共有 95 人阅读

第一章脑卒中(俗称中风)防治入门知识

第一单元测试

1、单选题：
‌脑卒中是哪个疾病的学名？ ‌
选项：
A: 脑梗死
B: 脑出血
C: 脑中风
D: 脑栓塞
答案: 【 脑中风】点我阅读全文

本文共有 111 人阅读

第九讲

第一次单元测验

1、单选题：
‍下列哪项财务指标侧重衡量企业的偿债能力状况？‎‍‎‍‎
选项：
A: 总资产周转率
B: 流动比率
C: 净利润
D: 流动资产周转率
答案: 【 流动比率】点我阅读全文

本文共有 115 人阅读

第1章 绪论

1.4 行政管理学的研究对象与研究方法

1、单选题：
‎德国学者冯· 史坦因（Lorenzvon Stein）。他于1865年撰写了《行政学》一书，但他当时主要是在（）的意义上使用“行政学”一词的‎
选项：
A: 民法
B: 行政法
C: 经济法
D: 程序法
答案: 【 行政法】点我阅读全文

本文共有 120 人阅读

第一章绪论

课堂练习1

1、单选题：
‍如果一个问题或者任务不可计算，那么对这个问题或任务的描述哪一句是正确的（    ）‌
选项：
A: 无法将该问题或任务所需数据一次性装入内存进行计算
B: 该问题或任务所需计算时间是非线性增加的
C: 图灵机不可停机
D: 该问题或任务所需计算时间是线性增加的
答案: 【 图灵机不可停机】点我阅读全文

本文共有 226 人阅读

摄影后期理论概述

摄影艺术通感单元测试

1、单选题：
‎艺术是由（  ）和创造的对象组成。‎‎‎
选项：
A: 创造的思想
B: 创造的主体
C: 创造的单位
D: 创造的产物
答案: 【 创造的主体】点我阅读全文

本文共有 100 人阅读

第一章绪论

第一章单元测验

1、多选题：
‏葡萄栽培学是果树学（Pomology）的一个分支，通常包括种类、品种和从育苗、建园直至采收各个环节的（）、（）和（）。‍
选项：
A: 基本理论
B: 基本知识
C: 基本技术
D: 实验方法
答案: 【 基本理论;
基本知识;
基本技术】点我阅读全文

本文共有 102 人阅读

第一章 民航基础常识

第一章

1、判断题：
​国际民航组织是联合国负责管理和发展国际民航事务的机构,国际航空运输协会则是国际性的民间组织。‎​‎
选项：
A: 正确
B: 错误
答案: 【 正确】点我阅读全文

本文共有 119 人阅读

第一章概述

第一章单元测试

1、单选题：
‏根据Kerchoffs假设，密码体制的安全性仅依赖于对       的保密，而不应依赖于对密码算法的保密。​
选项：
A: 密码算法
B: 密文
C: 明文的统计特性
D: 密钥
答案: 【 密钥】点我阅读全文

本文共有 139 人阅读