大学英语四级改革适用(阅读)模拟试卷288及答案解析.doc
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1、大学英语四级改革适用(阅读)模拟试卷 288及答案解析(总分:60.00,做题时间:90 分钟)一、Reading Comprehensio(总题数:8,分数:60.00)1.Part III Reading Comprehension_2.Section A_The ability to see words on either side of the point at which your eyes focus is called peripheral vision (外围视觉). Foreign students of English often feel that it is impos
2、sible to recognize so many words at a single 1or within a short time. It is difficult for many 2speakers too, but it can be done. It is something that has to be done if you are to read as 3as you should. You can increase your peripheral vision by eye exercises. Equally important is the importance of
3、 moving your eyes from point to point in a uniform rhythm. Slow reading often 4from regression, the number of times your eyes have to go back. While practising to increase your peripheral vision and uniform rhythm, you may 5have to reread. Do not get 6. A smooth, forward rhythm comes with practice.
4、7your speed will get to the point where your eyes move comfortably forward without regression. A final 8of slow reading is forming the sounds of each word, even though you might not speak them aloud. The 9American native speaks English at 180 to 200 words a minute. If you read each word in 10, it is
5、 impossible to read faster than this. Reading 200 words a minute is a dangerously slow speed. A. average B. eventually C. results D. column E. discouraged F. rapidly G. subsequent H. glance I. mind J. scratched K. process L. native M. occasionally N. cause O. offends(分数:20.00)填空项 1:_填空项 1:_填空项 1:_填空
6、项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_填空项 1:_4.Section B_GPS A) The Global Positioning System is a. space-based triangulation system using satellites and computers to measure positions anywhere on earth. It is first and foremost a defense system developed by the United States Department of Defense
7、, and is referred to as the “Navigation Satellite Timing and Ranging Global Positioning System“ or NAVSTAR GPS. The uniqueness of this navigational system is that it avoids the limitations of other land-based systems such as limited geographic coverage, lack of continuous 24-hour coverage, and the l
8、imited accuracies of other related navigational instruments. The high accuracies obtainable with the Global Positioning System also make it a precision survey instrument. GPS Components: the Space Segment, the Control Segment, and the User Segment. B) The Space Segment of the system consists of the
9、GPS satellites. These space vehicles (SVs) send radio signals from space. The GPS Operational Constellation consists of 24 satellites that orbit the earth in 12 hours. There are often more than 24 operational satellites as new ones are launched to replace older satellites. The satellite orbits repea
10、t almost the same ground track (as the earth turns beneath them) once each day. The orbit altitude is such that the satellites repeat the same track and area over any point approximately each 24 hours (4 minutes earlier each day). There are six orbital planes (with four SVs in each), equally spaced
11、(60 degrees apart), and inclined at about fifty-five degrees with respect to the equatorial (赤道的) plane. This constellation provides the user with between five and eight SVs visible from any point on the earth. C) The Control Segment consists of a system of tracking stations located around the world
12、. The Master Control facility is located at Schriever Air Force Base (formerly Falcon AFB) in Colorado. These monitor stations measure signals from the SVs which are incorporated into orbital models for each satellites. The models compute precise orbital data and SV clock corrections for each satell
13、ite. The Master Control station uploads orbital data and clock data to the SVs. The SVs then send subsets of the orbital ephemeris (星历表) data to GPS receivers over radio signals. D) The GPS User Segment consists of the GPS receivers and the user community. GPS receivers change SV signals into positi
14、on, speed, and time estimates. Four satellites are required to compute the four dimensions of X, Y, Z (position) and Time. GPS receivers are used for navigation, positioning, time distribution, and other research. Navigation in three dimensions is the primary function of GPS. Navigation receivers ar
15、e made for aircraft, ships, ground vehicles, and for hand carrying by individuals. Precise positioning is possible using GPS receivers at reference locations providing corrections and relative positioning data for remote receivers. Surveying, geodetic control, and plate tectonic studies are examples
16、. E) Time and frequency distribution, based on the precise clocks on board the SVs and controlled by the monitor stations, is another use for GPS. Astronomical observatories, telecommunications facilities, and laboratory standards can be set to precise time signals or controlled to accurate frequenc
17、ies by special purpose GPS receivers. Research projects have used GPS signals to measure atmospheric parameters. F) At present the system consists of 24 satellites at an altitude of about 20,000 km having an orbital inclination of 55 degrees. The orbits are almost circular and it takes 12 hours for
18、a satellite to complete a pass around the Earth. GPS signals are broadcast from a cluster of 24 or more earth orbiting satellites. Because the GPS signals are derived from the atomic frequency standards on board each satellite, they are widely used as a reference for time synchronization and frequen
19、cy adjustment. The real time positioning accuracy of a single receiver is normally up to 100 meters horizontally and 150 meters vertically. However, various methods have been developed which enable much higher accuracy (centimeter level). G) There are a variety of different types of GPS receivers on
20、 the market for commercial and public use. Prices range from $500 to $30,000, reflecting the accuracy and capabilities of the instruments. For the general outdoorsman, a good GPS receiver should have 8 satellite tracking capability and be capable of receiving the GPS satellite signals through forest
21、 covering in northern Ontario shield area; for the professional user, a minimum 8 satellite tracking capability, high memory capacity, differential GPS capability, and resistance to signal weakening under forest covering is essential; for the professional surveyor requiring high level precision and
22、accuracy capability, they should assess the project or application for which the technology is to be used with the help of an unbiased consultant, in order to determine the most cost effective and appropriate instrument. H) Small hand held navigational units at relatively low cost allow boaters and
23、hikers to know their position within a few hundred meters. This accuracy is sufficient for recreational use. A hand held or similar mapping unit at mid-range price that is linked to a fixed broadcast base station. These units allow utility companies, municipalities and others to locate various items
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