mooc答案类别订阅

第一次单元测试

1、单选题：

​杂化轨道之间的键角是[          ].

‏选项：
A: 90°
B: 109.5° 
C: 120°
D: 180°
答案: 【 120°】点我阅读全文

第一周测试

1、单选题：
‎项目投资就是以（  ）为特定目的，将一定数量的货币、资本及实物投放于指定项目，在未来相当长时间里获得预期收益的经济活动‌
选项：
A: 投资形式
B: 投资主体
C: .投资客体
D: 投资资源
答案: 【 投资主体】点我阅读全文

1.1测量学简介

1、多选题：
​ 测量界中有“3S”之说，这里的“3S”是指：‍
选项：
A: GPS（Global Positioning System）
B: ETS（Electronic Total Station）
C: RS（Remote Sensing）
D: GIS（Geographic Information System）
答案: 【 GPS（Global Positioning System）;
RS（Remote Sensing）;
GIS（Geographic Information System）】点我阅读全文

第二讲自测

1、单选题：
‌青年鲁迅主要是在▁▁一文里呈现他对“反叛—抗世”型生命方式的心仪。‍
选项：
A: 《人之历史》
B: 《文化偏至论》
C: 《破恶声论》
D: 《摩罗诗力说》
答案: 【 《摩罗诗力说》】点我阅读全文

向量及其线性运算测试

1、单选题：
‌下列物理量中，不是向量的是______. ‏
选项：
A: 位移
B: 速度
C: 力
D: 功
答案: 【 功】点我阅读全文

第二章测试

1、单选题：

​一物体在1秒内沿半径R=1m的圆周上从A点运动到B点，如图所示，则物体的平均速度是：

‌

​

‌选项：
A: 大小为2m/s，方向由A指向B；
B: 大小为2m/s，方向由B指向A；
C: 大小为3.14m/s，方向为A点切线方向；
D: 大小为3.14m/s，方向为B点切线方向。
答案: 【 大小为2m/s，方向由A指向B；】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

随堂测验1

1、单选题：
‌在下列账户中，与负债类账户结构相同的是（    ）账户‎
选项：
A: 资产类
B: 成本类
C: 费用类
D: 所有者权益类
答案: 【 所有者权益类】点我阅读全文

随堂测试

1、填空题：
​卜算子·我住长江头是谁的作品？‍
答案: 【 宋代词人李之仪】点我阅读全文