mooc答案类别订阅

第一章 单元测验

1、单选题：
​手机属于。‎
选项：
A: 机械
B: 机构
C: 机器
D: 即不属机构，也不属机器
答案: 【 机器】点我阅读全文

第一周单元测试

1、单选题：
学前教育的对象是指哪一个年龄段的儿童？（    ）​‌​
选项：
A: 0--6岁 
B: 0--3岁 
C: 0--12岁 
D: 3--6岁
答案: 【 0--6岁 】点我阅读全文

第1章单元测试

1、单选题：
‍下列哪项不是信息技术的三大支柱（）‏
选项：
A: 通信技术
B: 测试技术与传感器技术
C: 控制技术
D: 计算机技术
答案: 【 控制技术】点我阅读全文

手绘基础知识

1、单选题：

​下图所示为哪种透视？

‍

​

‍选项：
A: 一点透视 
B: 两点透视
C: 三点透视
D: 鱼眼透视
答案: 【 一点透视 】点我阅读全文

第1讲单元测试

1、单选题：
‍在数据模型中，对数据静态特性描述的是‎
选项：
A: 数据结构
B: 数据操作
C: 数据完整性
D: 数据模式
答案: 【 数据结构】点我阅读全文

第一章章节测试

1、单选题：

‍

‏选项：
A: A
B: B
C: C
D: D
答案: 【 C】点我阅读全文

计算机基础知识与相关概念

1、单选题：
‎世界上第一台全自动电子数字计算机ENIAC的诞生时间是（）。‎
选项：
A: 1945年
B: 1946年
C: 1948年
D: 1949年
答案: 【 1946年】点我阅读全文

第1章单元测验

1、单选题：
‎《船舶结构力学》主要研究结构的（    ）响应。‎
选项：
A: 静力
B: 动力
C: 应力
D: 位移
答案: 【 静力】点我阅读全文

随堂测验

1、单选题：
​STP的端口状态的变化顺序是：‌
选项：
A: Blocking ，learing ，listening ，forwarding
B: Blocking ，learing ，forwarding ，listening
C: Blocking ，listening ，learing ，forwarding
D: Blocking ，forwarding ，listening ，learing
答案: 【 Blocking ，listening ，learing ，forwarding】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