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实际工作中的成本开支范围与理论成本包括的内容是。

1、单选题：
​实际工作中的成本开支范围与理论成本包括的内容是      。‎
选项：
A: 有一差别的
B: 完全一致的
C: 两个不同概念
D: 可以相互替代
答案: 【 有一差别的】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

单元测验

1、单选题：
‏关于信息社会，下列说法不正确的是(   )‍
选项：
A: 计算机的发明和广泛使用是人类社会进入信息社会的唯一标志。
B: 信息社会中所有的工业生产都是自动化的。
C: 在信息社会，信息技术催生大批新兴产业，同时，传统产业也普遍实行技术改造。
D: 信息社会中信息产业高度发展，在产业结构优势的地位日益突出。
E: 在信息社会，信息、知识成为重要的生产力要素。
F: 信息社会是从20世纪中叶开始的，又称后工业社会。
G: 计算机的发明是第三次科技革命的重要标志，是人类文明史上继蒸汽技术革命和电力技术革命之后科技领域里的又一次重大飞跃。
答案: 【 计算机的发明和广泛使用是人类社会进入信息社会的唯一标志。;
信息社会中所有的工业生产都是自动化的。】点我阅读全文

第一周单元测验

1、单选题：
‍经常账户各项目都是按（）记录。​‍​‍​
选项：
A: 总额
B: 差额
C: 净额
D: 余额
答案: 【 总额】点我阅读全文

1.3.1 平面的方程 随堂测验

1、单选题：

‎

‍选项：
A:
B:
C:
D:
答案: 【 】点我阅读全文

第一讲测验

1、单选题：
‎除了单片机这一名称之外，单片机还可称为(     )。​
选项：
A: CPU
B: 嵌入式微控制器
C: 微处理器
D: 微处理机
答案: 【 嵌入式微控制器】点我阅读全文

测验01淘宝开店考试题选

1、单选题：
‏违反交通法规的商品淘宝网禁止出售，以下哪种属于该范畴？‏
选项：
A: 充电插座
B: 汽车坐垫
C: 牌照喷剂
D: 车载电视
答案: 【 牌照喷剂】点我阅读全文

随堂测验

1、单选题：
5．根据控制系统元件的特性，控制系统可分为（       ）‌‌‍‌
选项：
A:  反馈控制系统和前馈控制系统
B: 线性控制系统和非线性控制系统
C: 定值控制系统和随动控制系统
D: 连续控制系统和离散控制系统
答案: 【 线性控制系统和非线性控制系统】点我阅读全文

共用体练习

1、单选题：
当定义一个共用体变量时，系统分配给它的内存是（   ）。‏‏
选项：
A: 各成员所需内存量的总和
B: 成员中占内存量最大的容量
C: 结构中第一个成员所需内存量  
D: 结构中最后一个成员所需内存量
答案: 【 成员中占内存量最大的容量】点我阅读全文

第一章单元测验

1、单选题：
‌Python语言正确的标识符是‎
选项：
A: 2you
B: my-name
C: _item
D: abc*234
答案: 【 _item】点我阅读全文