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定积分的性质测试

1、单选题：

​

‏选项：
A:
B:
C:
D:
答案: 【 】点我阅读全文

1.初识税务会计单元测验

1、单选题：
‍以下不属于税务会计对象的有（     ）。‌
选项：
A: 税目
B: 计税依据
C: 税款的缴纳、退补与减免
D: 生产成本的计算
答案: 【 生产成本的计算】点我阅读全文

模块一实验三测验

1、单选题：

‏在显微镜下观察到如下结果，这是（      ）菌的标准切片。

‏

‏

‏选项：
A: 根霉
B: 青霉
C: 酵母菌
D: 芽孢杆菌
答案: 【 青霉】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

第一章单元测试

1、单选题：
1、对一类负荷的供电要求是        。​‍‍​
选项：
A: A、至少两个独立电源 
B: B、两回输送线路  
C: C、一条输送线 
D: D、没有要求 
答案: 【 A、至少两个独立电源 】点我阅读全文

第1章投影法及其应用检测题

1、单选题：

‍下图借鉴了哪种工程常用的投影图？

​

‍

​选项：
A: 标高投影图
B: 透视图
C: 轴测图
D: 多面正投影图
答案: 【 轴测图】点我阅读全文

第一单元课堂测试

1、单选题：
​⑵广告创意是指：1、一个好的创造意图。2、创作出一个意念。3、创造性地想出一个好主意、好点子。4、创作出一个好作品.‎
选项：
A: 一个好的创造意图。
B: 创作出一个意念。
C: 创造性地想出一个好主意、好点子。
D: 创作出一个好作品.
答案: 【 创造性地想出一个好主意、好点子。】点我阅读全文

单元测验一

1、单选题：

‎

‎选项：
A:
B:
C:
D:
答案: 【 】点我阅读全文

1.2微分方程基本概念随堂测验

1、单选题：

‍

​选项：
A:
B:
C:
D:
答案: 【 】点我阅读全文

第2周小测验

1、填空题：
写出以下代码段的执行结果：​int num=34, max=30;
if ( num >= max*2 )
    System.out.println("zhang");
    System.out.println("huang");
System.out.println("zhu");​‎​
答案: 【 huang
zhu】点我阅读全文