問題詳情

31-34)Imagine the situation. You are driving along a desert or on a mountain. You have no idea where you are. You passed thelast house two hours ago. Then your car breaks down. It is night and it is cold. You have no cellphone. What do you do? Well,next time take a GPS with you. This invention may be able to help you. It is a device(裝置) which uses satellites (衛星) to findthe user’s position. It can find your position to within 20 meters. A GPS cannot start your car, but at least you will know whereyou are.GPS, which means Global Positioning System, is a small radio receiver(接受器). It looks like a cellphone. You can hold itin your hand, or put in your pocket. It is sometimes put into a watch or a telephone. We also find GPS devices in cars, planes, orboats. Some of these devices have electronic(電子的) maps, so you know where you are. For example, in a city they can tellyou the name of the street.There are three parts to the Global Positioning System. The first part is the receiver. You can hold it in your hand, or haveit fixed into your car, plane, etc. The second part is a group of satellites orbiting(繞軌道運行) the Earth. The receivercontacts(接觸) at least four of the satellites and calculates(計算) its position. The third part of the system is a network ofground stations. They are all over the world. They control the satellites and make sure they are working well.Some people think that in the future the GPS will be as common as the cellphone. There are also new uses for the GPS.Perhaps they will become like watches. Everyone will have one and you will never be lost again.
31. According to the reading, there are _____ parts to the GPS.
(A) one
(B) two
(C) three
(D) four

參考答案

答案：C
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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