CImaginethesituation.Youaredrivingaloneinadesertoronamountain.Youhavenoideawhereyouare.Youpassedthelasthousetwohoursago.Thenyourcarbreaksdown.Itisnightanditiscold.Youhaveno

Question

                 C 

    Imagine the situation. You are driving alone in a desert or on a mountain. You have no idea where you are. You passed the last house two hours ago. Then your car breaks down. It is night and it is cold. You have no mobile phone. What do you do? Well next time take a GPS with you. This invention may be able to help you. It is a device (装置） which uses satellites (卫星) to find the user’s position (位置) .It can find your position within 20 metres. A GPS cannot start your car but at least you will know where you are.

   GPS which means Global Positioning System is a small radio receiver. It looks like a mobile phone. You can hold it in your hand or put it in your pocket. It is sometimes put into a watch or a telephone. We also find GPS devices in cars planes or boats. Some of these devices have electronic maps so you know where you are. For example in a city they can tell you 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 have it fixed into your car plane etc. The second part is a group of satellites orbiting the Earth. The receiver contacts at least four of the satellites and calculates (计算) its position. The third part of the system is a network of ground 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 mobile. They are becoming cheaper and more and more accurate (精确的) .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.

46. According to the passage with the help of the GPS people .

   A. can’t be lost in a new city

   B. can’t find their way in different countries

   C. can learn about the culture of an unknown place

   D. can spend the least time getting to another place

47. We can learn from the passage that .

   A. there are three parts to the GPS

   B. a GPS can’t be put into a watch

   C. a GPS can help you start your car

   D. the GPS is becoming more and more expensive

48. The underlined word “ They ” in Paragraph 3means “ ”

   A. Receivers     B. GPS devices

   C. Satellites   D. Ground stations

49. The passage is mainly about.

   A. the history of the GPS

   B. the introduction of the GPS

   C. the shape of the GPS

   D. the three parts of the GPS

50. What can we infer (推断) from the passage?

   A. All GPS devices have electronic maps.

   B. People in many countries will use the GPS for free.

   C. The receiver of the GPS contacts at least five of the satellites.

   D. The GPS will become more and more common in everyday life.

Answer 1

46. A GPS是全球定位系统，它能准确确定你所在的位置，在 它的帮助下，人们就不会在陌生的地方迷路了，故选A.

47. A 由短文第三段“There are three parts to…”知全球定位系 统有三个部分，故选A.

48. D由第三段知，GPS的第三部分是世界各地的地面基站网 络，地面基站控制着卫星，并确保卫星能正常运转，所以这里 的They是指地面基站。

49. B通读全文知，短文主要是向读者介绍了全球定位系统 GPS，故选B.

50. D从最后一段可知，全球定位系统将广泛应用于日常生活 中，它会像手机和手表一样普遍，由此可推出GPS将会在人 们的日常生活中很常见，故选D.