题目内容
（请给出正确答案）
A．He recently injured his hand
B．He can carry some books for the woman
C．He needs to borrow some of the woman's books
D．He can't help the woman until noon
简答题官方参考答案
（由简答题聘请的专业题库老师提供的解答）
更多“A．He recently injured his handB．He can carry some books for the womanC．He needs to bor”相关的问题
A. Shipment on or about July 2.
B. Shipment on June 20.
C. Shipment as soon as possible.
D. Shipment to be made during the middle of September,2003.
A、common-gate
B、common-drain
C、common-source
D、None of the above
B．He"ll complete me report when me computer"s fixed.
C．The report was much longer than he thought it would be.
D．The report was finished a couple of day ago.
A．To explain how a wall can be made stronger
B．To describe the process of framing a mural
C．To explain how to create an insulating air space
D．To describe a technique for texturing a plaster wall
A．large
B．dangerous
C．steady
D．unexpected
A．Square Ａ.
B．Square Ｂ.
C．Square Ｃ.
D．Square Ｄ.
B．He is studying to be a doctor.
C．An important new medical treatment may be available soon.
D．He has already tried the new medicine.
A．It involved stages of production.
B．It was more efficient than the systems used before 1790.
C．It made many employers less powerful than they had been before.
D．It did not necessarily involve any technological improvements.
听力原文： What is GPS？ Its full name is the Global Positioning System and a satellite-based navigation system. Generally speaking, it is made up of a network of 24 satellites placed into orbit by the U. S. Department of Defense. GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. Nowadays, GPS works in any weather conditions, anywhere in the world, 24 hours a day. There are no subscription fees or setup charges to use GPS. How does it work？ At first, GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. Secondly, GPS receivers take this information and use triangulation to calculate the users exact location. Essentially, the GPS receiver compares two times, one is the time a signal was transmitted by a satellite; the other is the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the users position and display it on the units electronic map. A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position and track movement. With four or more satellites in view, the receiver can determine the users 3D position, here three dimensions are latitude, longitude and altitude. Once the users position has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time and more. How accurate is GPS？ Todays GPS receivers are extremely accurate, thanks to their parallel multi-channel design. Garmins 12 parallel channel receivers are quick to lock onto satellites when first turned on and they maintain strong locks, even in dense foliage or urban settings with tall buildings. Certain atmospheric factors and other sources of error can affect the accuracy of GPS receivers. Garmin GPS receivers are accurate to within 15 meters on average. How about the Newer Garmin GPS receivers？ With WAAS, that is Wide Area Augmentation System, its capability can improve accuracy to less than three meters on average. No additional equipment or fees are required to take advantage of WAAS. Users can also get better accuracy with Differential GPS, which corrects GPS signals to within an average of three to five meters. The U. S. Coast Guard operates the most common DGPS correction service. This system consists of a network of towers that receive GPS signals and transmit a corrected signal by beacon transmitters. In order to get the corrected signal, users must have a differential beacon receiver and beacon antenna in addition to their GPS. GPS satellites are powered by solar energy. They have backup batteries onboard to keep them running in the event of a solar eclipse, when theres no solar power. Small rocket boosters on each satellite keep them flying in the correct path. Here are some other interesting facts about the GPS satellites, also called NAVSTAR by the official of U. S. Department of Defense. the first GPS satellite was launched in 1978; a full constellation of 24 satellites was achieved in 1994; each satellite is built to last about 10 years. Replacements are constantly being built and launched into orbit; A GPS satellite weighs approximately 2000 pounds and is about 17 feet across with the solar panels extended; transmitter power is only 50 watts or less.Narrator Listen to part of a lecture about GPS. Now get ready to answer the questions. You may use your notes to help you answer.
What aspect of GPS does the talk mainly discuss？
A．What it is made up of and its shortcomings
B．How it works and its attributes.
C．The history of its development.
D．How it is different from other technologies.
警告：系统检测到您的账号存在安全风险
为了保护您的账号安全，请在“简答题”公众号进行验证，点击“官网服务”-“账号验证”后输入验证码“”完成验证，验证成功后方可继续查看答案！
