2. Imagine the situation. You are driving along 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 to find the user’s position. It can find your position in 20 meters. A GPS can’t 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(围绕) the earth. The receiver contacts at least four of the satellites and calculates 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(精准). There are also many new uses for the GPS. Perhaps they will become like watches. Everyone will have one and you will never be lost again.
【小题1】 With the help of GPS, people ______.
| A．can’t be lost in a new city |
| B．can’t find their way in different countries |
| C．can start the car |
| D．can learn about the culture of an unknown place |
【小题2】 GPS means ___________in Chinese
| A．球状卫星 | B．卫星地点 |
| C．全球卫星定位系统 | D．接收器 |
【小题3】______is not the part to the Global Positioning System.
| A．ground stations | B．satellites |
| C．receivers | D．a mobile |
【小题4】 Maybe in the future the GPS will be _________.
| A．cheaper than mobile phones | B．as common as watches. |
| C．having few new uses | D．more accurate than now. |
【小题5】. From the passage we know that ______.
| A．people can drive along a desert easily. |
| B．All GPS devices have electronic maps |
| C．Ground stations control the satellites and make sure they are working well. |
| D．Everyone will use the GPS for free. |
