1、大学英语六级模拟试卷 806及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a short essay entitled Scientific Breakthroughs in China. You should write at least 150 words following the outline given below: The number of scientific breakthroughs over the past years in Chin
2、a(Estimated) 1上图所示为中国近几年的科学创新情况，请描述其变化 2请说明发生这些变化的原因 3对此进行预测 Scientific Breakthroughs in China 二、 Part II Reading Comprehension (Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For
3、 questions 1-4, mark： Y (for YES) if the statement agrees with the information given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 Satellite TV Today, you see compact satellite dishes
4、 perched on rooftops all over the United States. Drive through rural areas beyond the reach of the cable companies and youll find dishes on just about every house. The major satellite television companies are bringing in more customers every day with the lure of movies, sporting events and news from
5、 around the world. The Broadcast TV Problem Conceptually, satellite television is, a lot like broadcast television. Its a wireless system for delivering television programming directly to a viewers house. Both broadcast television and satellite stations transmit programming via a radio signal. Broad
6、cast stations use a powerful antenna to transmit radio waves to the surrounding area. Viewers can pick up the signal with a much smaller antenna. The main limitation of broadcast television is range. The radio signals used to broadcast television shoot out from the broadcast antenna in a straight li
7、ne. In order to receive these signals, you have to be in the direct “line of sight“ of the antenna. One problem is that the Earth is curved, so it eventually breaks the signals line of site. The other problem with broadcast television is that the signal is often distorted even in the viewing area. T
8、o get a perfectly clear signal like you find on cable, you have to be pretty close to the broadcast antenna without too many obstacles in the way. The Satellite TV Solution Satellite television solves the problems of range and distortion by transmitting broadcast signals from satellites orbiting the
9、 Earth. Since satellites are high in the sky, there are a lot more customers in the line of site. Satellite television systems transmit and receive radio signals using specialized antennas called satellite dishes. The television satellites are all in geosynchronous orbit, meaning that they stay in o
10、ne place in the sky relative to the Earth. Each satellite is launched into space at about 7,000 mph(11,000 kph), reaching approximately 22,200 miles(35,700 km)above the Earth. At this speed and altitude, the satellite will revolve around the planet once every 24 hoursthe same period of time it takes
11、 the Earth to make one full rotation. In other words, the satellite keeps pace with our moving planet exactly. This way, you only have to direct the dish at the satellite once, and from then on it picks up the signal without adjustment, at least when everything works right. The Overall System Early
12、satellite TV viewers were explorers of sorts. They used their expensive dishes to discover unique programming that wasnt necessarily intended for mass audiences. The dish and receiving equipment gave viewers the tools to pick up foreign stations, live feeding between different broadcast stations, NA
13、SA activities and a lot of other stuff transmitted using satellites. Some satellite owners still seek out this sort of programming on their own, but today, most satellite TV customers get their programming through a direct broadcast satellite(DBS)provider, such as Direct TV or the Dish Network. The
14、provider selects programs and broadcasts them to subscribers as a set package. Basically, the providers goal is to bring dozens or even hundreds of channels to your television in a form that approximates the competition, cable TV. Unlike earlier programming, the providers broadcast is completely dig
15、ital, which means it has much better picture and sound quality. Early satellite television was broadcast in C-band radio radio in the 3. 4-gigabertz(GHz)to 7-GHz frequency range. Digital broadcast satellite transmits programming in the Ku frequency range(12 GHz to 14 GHz). The Programming Satellite
16、TV providers get programming from two major sources: national turnaround channels(such as HBO, ESPN and CNN)and various local channels(NBC, CBS, ABC, PBS and Fox affiliates in a particular area). Most of the turnaround channels also provide programming for cable television, and the local channels ty
17、pically broadcast their programming over the airwaves. Turnaround channels usually have a distribution centre that beams their programming to a geostationary satellite. The broadcast centre uses large satellite dishes to pick up these analogs and digital signals from several sources. The broadcast c
18、entre converts all of this programming into a high-quality, uncompressed digital stream. At this point, the stream contains a vast quantity of dataabout 270 megabits per second(Mbps)for each channel. In order to transmit the signal from there, the broadcast centre has to compress it. Otherwise, it w
19、ould be too big for the satellite to handle. Compression, Encryption and Transmission The two major providers in the United States use the MPEG-2 compressed video format the same format used to store movies on DVDs. With MPEG-2 compression, the provider can reduce the 270-Mbps stream to about 5 or 1
20、0 Mbps(depending on the type of programming). This is the crucial step that has made DBS service a success. With digital compression, a typical satellite can transmit about 200 channels. Without digital compression, it can transmit about 30 channels. At the broadcast centre, the high-quality digital
21、 stream of video goes through an MPEG-2 encoder, which converts the programming to MPEG-2 video of the correct size and format for the satellite receiver in your house. After the video is compressed, the provider needs to encrypt it in order to keep people from accessing it for free. Encryption scra
22、mbles the digital data in such a way that it can only be decrypted(converted back into usable data)if the receiver has the correct decryption algorithm and security keys. Once the signal is compressed and encrypted, the broadcast centre beams it directly to one of its satellites. The satellite picks
23、 up the signal with an onboard dish, amplifies the signal and uses another dish to beam the signal back to the Earth, where viewers can pick it up. The Dish and the Receiver A satellite dish is just a special kind of antenna designed to focus on a specific broadcast source. The standard dish consist
24、s of a parabolic(bowl-shaped)surface and a central feed horn. To transmit a signal, a controller sends it through the horn, and the dish focuses the signal into a relatively narrow beam. The end component in the entire satellite TV system is the receiver. The receiver has four essential jobs: It de-
25、scrambles the encrypted signal. In order to unlock the signal, the receiver needs the proper decoder chip for that programming package. It takes the digital MPEG-2 signal and converts it into an analog format that a standard television can recognize. In the United States, receivers convert the digit
26、al signal to the analog NTSC format. Some dish and receiver setups can also output an HDTV signal. It extracts the individual channels from the larger satellite signal. When you change the channel on the receiver, it sends just the signal for that channel to your TV. It keeps track of pay-per-view p
27、rograms and periodically phones a computer at the providers headquarters to communicate billing information. While digital broadcast satellite service is still lacking some of the basic features of conventional cable(the ability to easily split signals between different TVs and VCRs. for example), i
28、ts high-quality picture, varied programming selection and extended service areas make it a good alternative for some. With the rise of digital cable, which also has improved picture quality and extended channel selection, the TV war is really heating up. 2 Broadcast stations use_to transmit radio wa
29、ves to the surrounding area. （ A） a powerful antenna （ B） a much smaller antenna （ C） satellite dishes （ D） cable 3 The television satellites stay in geosynchronous orbit and_. （ A） transmit signal in the direct “line of sight“ （ B） compress the signal （ C） keep pace with the moon （ D） keep pace wit
30、h the earth 4 In recent years. satellite television has started to be broadcast in the radio frequency range_. （ A） between 3. 4 GHz and 7 GHz （ B） between 12 GHz and 14 GHz （ C） between 14 GHz and 21 GHz （ D） between 21 GHz and 27GHz 5 Local television channels usually use_to transmit their program
31、ming. （ A） satellites （ B） cable （ C） airwaves （ D） wires 6 Satellite television providers can bring dozens or even hundreds of channels to TV viewers because_. （ A） satellite can send more programs （ B） the television signals sent to satellites are compressed （ C） the signals are encrypted （ D） the
32、 signals converted back into usable data 7 _receives satellite television signal and decodes it for the TV screen. （ A） The satellite dish （ B） The provider （ C） The receiver （ D） The viewer 8 Satellite TV has encountered fierce competition from digital cable, which also has_. （ A） improved picture
33、quality （ B） extended channel selection （ C） distorted signal （ D） both A and B 9 Satellite television is similar to broadcast television in the way that it is _ for sending television programming directly to a viewers home. 10 In the United States, the two major providers of direct broadcast satell
34、ite television are_. 11 The satellite television signal is transmitted in the digital video format of_. Section A Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both
35、the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer. （ A） She thinks the price is too high. （ B） She thinks the price is quite normal. （ C） S
36、he thinks the price could be cheaper. （ D） She thinks the price is really low. （ A） Take a walk. （ B） Give a performance. （ C） Listen to the music. （ D） Dance to the music. （ A） Tell the woman something about the car. （ B） Look for his wife. （ C） Show the woman his wifes car. （ D） Ask his wife to an
37、swer the phone. （ A） The woman will reserve a restaurant for the dinner. （ B） Mary King will decide where they have their dinner. （ C） The man will decide where to have dinner with Mary King. （ D） The woman suggests that the man should ask Mary King. （ A） They will definitely buy a new car. （ B） The
38、y will not buy a new car because they dont have enough money. （ C） They will buy a new car for their vacation. （ D） They will buy a new car when they return from their vacation. （ A） He is very forgetful. （ B） He likes to play tricks. （ C） His tests are difficult. （ D） It is easy to pass his course.
39、 （ A） A book. （ B） A watch. （ C） A case for his coin collection. （ D） Nothing. （ A） He will probably come another time. （ B） He will bring enough money to buy the ticket. （ C） He will probably go to Los Angeles by train. （ D） He will probably get a ticket on Delta or Trans World Airlines. （ A） To co
40、nfirm that the man is capable of beating Clement. （ B） To show how sincere he is. （ C） To give an example of how to run fast. （ D） To make a joke about the mans comment. （ A） The answer is close but not exactly correct. （ B） The answer is totally out of target. （ C） The answer is really correct. （ D
41、） The answer is too obvious. （ A） 19 years old. （ B） 13 years old. （ C） 15 years old. （ D） 17 years old. （ A） Movie on Display. （ B） Movie on the Show. （ C） Best-selling Movie. （ D） Shining Movie Stars. （ A） It tops the U. S. annual box office. （ B） Its main character is an advertising executive. （
42、C） The main actor is Tom Cruise. （ D） It is an old-fashioned silly comedy. （ A） Gibson is very popular with audience. （ B） Gibson is experienced in playing feminine roles. （ C） Gibson has the necessary ability for the role. （ D） Gibson interprets the role to Meyers satisfaction. （ A） Men should reme
43、mber whatever women say. （ B） Men should give women whatever they want. （ C） Women give it when men fail to catch what they say. （ D） Women appreciate it when men make an effort to understand them. Section B Directions: In this section, you will hear 3 short passages. At the end of each passage, you
44、 will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D. （ A） They were born to be pale. （ B） They did not like traveling in sunny countries. （ C） They wanted to be d
45、ifferent from the peasants. （ D） They thought light color was the color of health. （ A） People without exposure to sunlight. （ B） Wealthy people in Europe centuries ago. （ C） Workers during the Industrial Revolution. （ D） Wealthy people during the Industrial Revolution. （ A） Noblemen centuries ago d
46、id not like traveling. （ B） Heredity is not the only thing that influences our color. （ C） Exposure to sunlight is the only thing that determines skin color. （ D） Having a tan is considered a sign of wealth nowadays in North America. （ A） Sort the mail. （ B） Answer the mail. （ C） Read the magazines.
47、 （ D） File important information. （ A） Pay the bills right away. （ B） Read the magazines very quickly. （ C） Sort the articles into categories for later reference. （ D） Stop buying magazines which you dont have time to read. （ A） At least once a month. （ B） At least twice a month. （ C） At least once
48、a year. （ D） At least twice a year. （ A） Call on people to protect sharks. （ B） Point out the living environment of sharks. （ C） Explain why the sharks are dangerous. （ D） An introduction to sharks. （ A） By good sense of water waves made by quarries. （ B） By good sense of smell and electrical magnet
49、ic power. （ C） By good sense of light. （ D） By good sense of blood. （ A） Bone structure. （ B） Smell ability. （ C） Birth mode. （ D） Recover ability against disease. （ A） Their tasty meat. （ B） The principle of their defense system against disease. （ C） Their solid skin. （ D） The principle of their birth modes. Section C Directions: In this section, you will hear a passage three times. When the passage is read for the first time, you should listen carefully for its general idea. When the
