智慧树慕课答案
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
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
1、单选题：
北方四合院、粤赣的客家土楼、草原上的蒙古包、丛林中的（ ），从民居的每一个角落我们都可以发现民间艺术。
选项：
A: 四合院
B: 客家土楼
C: 蒙古包
D: 吊角楼
答案: 【 吊角楼】点我阅读全文
1、单选题：
下面的那种美术学说是清代的著名画家石涛提出来的？
选项：
A: 模仿自然说
B: 师造化说
C: 搜尽奇峰打草稿
D: 再现现实说
答案: 【 搜尽奇峰打草稿】点我阅读全文
1、单选题：
1、礼仪起源于俗和（ ）
选项：
A: 风俗
B: 祭祀
C: 民间
D: 封建迷信
答案: 【 祭祀】点我阅读全文
1、单选题：
1. AC尼尔森尼尔森调查报告显示，大约（ ）的90后受访者表示他们每天至少上网一到两次。
选项：
A: A. 56%
B: B. 66%
C: C.76%
D: D. 86%
答案: 【 D. 86%】点我阅读全文
1、单选题：
成熟的动物血红细胞没有细胞核、细胞器和内膜系统，是研究质膜膜骨架的理想材料。请问以下哪组蛋白属于质膜骨架蛋白？
选项：
A: 血影蛋白，锚定蛋白，带4.1蛋白， 肌动蛋白, 内收蛋白
B: 带3蛋白，肌动蛋白，血影蛋白， 锚定蛋白, 内收蛋白
C: 血型糖蛋白，锚定蛋白，带4.1蛋白， 肌动蛋白, 内收蛋白
D: 带3蛋白，血型糖蛋白，带4.1蛋白，肌动蛋白, 内收蛋白
答案: 【 血影蛋白，锚定蛋白，带4.1蛋白， 肌动蛋白, 内收蛋白】点我阅读全文
1、单选题：
（ ）是一种驱动力，促使人们获得渴望的结果。
选项：
A: 动机
B: 态度
C: 情感
D: 需要
答案: 【 动机】点我阅读全文
1、单选题：
从关系营销的角度，市场应定义为（ ）
选项：
A: 市场是利益攸关者的集合
B: 市场是卖方、买方、竞争者的集合
C: 市场是某种商品的购买者集合
D: 市场是商品交换的场所
答案: 【 市场是利益攸关者的集合】点我阅读全文
