当前位置:网考网 >> 四六级考试 >> 试题查看
【单选题】
Television was not invented by any one person. Nor did it spring into being overnight. It evolved gradually, over a long period, from the ideas of many people -- each one building on the work of their predecessors. The process began in 1873, when it was accidentally discovered that the electrical resistance of the element selenium varied in proportion to the intensity of the light shining on it. Scientists quickly recognized that this provided a way of transforming light variations into electrical signals. Almost immediately a number of schemes were proposed for sending pictures by wire(it was, of course, before radio).
One of the earliest of these schemes was patterned on the human eye. Suggested by G. R. Carey in 1875, it envisioned a mosaic of selenium calls on which the picture to be transmitted would be focused by a lens system. At the receiving end there would be a similarly arranged mosaic made up of electric lights. Each selenium cell would be connected by an individual wire to the similarly placed light in the receiving mosaic. Light falling on the selenium cell would reproduce the original picture, had the necessary amplifiers and the right kind of lights been availablr, this system would have workrd. But it also would have required an imoractical number of connecting wires. Carey recognized this and in a second proposed to “scan” the cells-transmitting the signal from each cell to its associated light, in turn, over a single wire. If this were done fast enough, the retentive power of the eye would cause the resultant image to be seen as a complete picture.
41. Which of the following is the best title for the passage?
A. Television in the Electronic Era
B. First Steps in the Invention of Television
C. The Art of Television
D. Harmful Effects of Television Viewing
42. In line 1, the word “being” could best be replaced by _____.
A. place
B. creature
C. subsistence
D. existence
43. An important discovery in earlyteleviosion was the electrical resistance of _____.
A. mosaics
B. the human eye
C. lenses
D. the element selenium
44. In 1875, Carey suggested that the human eye envisioned a mosaic of selenium cells on which the picture to be transmitted would be focused by ______.
A. wire
B. electric lights
C. a lens system
D. amplifiers
45. Following are the reasons why the first scheme for television was abandoned except _____.
A. he lacks an effective assistant
B. the necessary amplifers were unavailable
C. the proper lights were unavailable
D. the number of connecting wires is impractical
正确答案
正在加载...
答案解析
正在加载...
根据网考网考试中心的答案统计,该试题:
0%的考友选择了A选项0%的考友选择了B选项0%的考友选择了C选项0%的考友选择了D选项
你可能感兴趣的试题
第1题:
&nBsp;iF you CAn provE to thE Court thAt johnson hAs()
roBEry,hE will BE FounD guilty.
A.CrEAtED
B.mADE
C.CommittED
D.CAusED
第2题:
Directions: In this part there is a short passage with five questions or incomplete statements.Read the passage carefully.Then answer the questions or complete the statements in less than 10 words.
Have you ever been asked to take a polygraph test for a job?A polygraph,also called a lie detector,is a device that is used to find out if someone is telling a lie.It is based on the belief that lying causes certain physical reactions.These reactions,which include a change in blood pressure and第3题:
Part Ⅴ Writing
Directions: For this part,you are allowed 30 minutes to write a composition based on the following outline (given in Chinese).The suggested title is: Private schools in China.You should write no less than 150 words for your composition.
提纲: 1.私立学校在中国的兴起。
2. 私立学校可能带来的好处。
1)人才市场的需要
2)培养一流人才
3)提高全民族科学,教育水平
3.更多的孩子会上私立学校。
第4题:
Animation means making things which are lifeless come alive and move.
From earlist times, people have always been facinated by movement, But not until this century have we managed to capture movement, to record it, and in the case of animation, to reinterpret it and recreate it. To do all this, we use a movie camera and a projector.
In the world of cartoon animation, nothing is impossible. You can make the characters you create do exactly what you want them.
A famous early第5题:
Questions 11 to 18 are based on the conversation you have just hearD、 A.She was not able to manage the project well.
B.She had managed to recover from the shock.
C.She was not sure about the mystery in the project.
D.She wasn’t sure how she could finish it so early.
第6题:
Passage Three
Questions 32 to 35 are based on the passage you have just hearD、 A.41.
B.410.
C.14.
D.214.