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第11章 测验

1、单选题：
1920年代末巴金发表了第一部小说_________。
选项：
A: 《新生》
B: 《家》.
C: 《灭亡》
D: 《萌芽》
答案: 【 《灭亡》】点我阅读全文

PN结的形成

1、单选题：
‌自建电场会‍
选项：
A: 阻止漂移
B: 阻止扩散
C: 增强扩散
D: 同时增强扩散和漂移
答案: 【 阻止扩散】点我阅读全文

ZGSOS[2]第二章进程管理单元测试A

1、单选题：
‏程序在独占处理器的情况下运行时：只要程序执行时的环境和初始条件相同，程序重复执行的结果相同，这称之为（      ）。​
选项：
A: 顺序性
B: 封闭性
C: 可再现性
D: 开放性
答案: 【 可再现性】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

三重积分的概念和性质测试

1、单选题：

‍

​选项：
A:
B:
C:
D:
答案: 【 】点我阅读全文

一、单选题

1、单选题：
‌社区给居民提供工作机会，属于社区功能中的（）。（题目来源：全国社会工作者职业水平考试教材编写组：《社会工作综合能力全真题库卷》，知识出版社）‌
选项：
A: A.社会参与功能
B: B.心理支持功能
C: C.“生产——消费——流通”的经济功能
D: D.社会控制功能
答案: 【 C.“生产——消费——流通”的经济功能】点我阅读全文

第一章 概论测验

1、单选题：
‌‎‌欧洲海关大会在定义国际运输中所使用的托盘时，表述的是该设备‎‌‎‌‎
选项：
A: 一般包括被托架分开的两个层面或由支脚支撑的单层
B: 其总高度恰好适于利用叉车和托盘对其进行搬运
C: 可以有或没有上层结构
D: 上述三项都是
答案: 【 上述三项都是】点我阅读全文

Test for Chapter 1

1、单选题：
‌Part I: Choose from the following groups of words the one you hear. Each of the words will be read once only. ‌‌‌
选项：
A: feel
B: fell
C: fill
D: fail
答案: 【 fill】点我阅读全文

第1章测验

1、单选题：
‍汉字应写成长仿宋体，其高度不应小于：‏‍‏
选项：
A: 5mm
B: 2.5mm
C: 3.5mm
D: 4.5mm
答案: 【 3.5mm】点我阅读全文

第二章测试

1、单选题：
‍根据1949年1月19日中共中央发出的关于外交工作的指示，对于对美国武官，因其直接援助国民党打内战，应该（         ）。‏
选项：
A: 驱逐出境
B: 派兵监视 
C: 予以保护
D:  逮捕候审
答案: 【 派兵监视 】点我阅读全文