Imagine the situation. You are driving a car along a desert or on a mountain. You have no idea
you are. You passed the last house two hours ago. Then your
breaks down. It is night and it is cold. You have no mobile phone. What do you do? Well, next time take a
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(位置). It can find your position to within 20 metres. A GPS cannot start your car, but at least you will
where you are.
GPS, which means Global Positioning System, is a small
receiver. It looks like a mobile phone. You can hold it in your hand, or put in your pocket. It is sometimes put into a watch or a
. We also find GPS devices in cars, planes, or boats. Some of these devices have electronic
, so you know where you are. For example, in a city they can tell you the name of the
.
There are
parts to the Global Positioning System. The first part is the
. You can either hold it in your hand
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
the satellites and make sure they are working well.
Some people think that in the future the GPS will be as
as the mobile. They are becoming
and more and more accurate(精确的). There are also new uses for the GPS. Perhaps they will become like
. Everyone will have one and you will never be lost again.
| 小题2: | | A．ship | B．car | C．train | D．plane |
|
| 小题3: | | A．watch | B．ring | C．clock | D．GPS |
|
| 小题4: | | A．advise | B．know | C．represent | D．speak |
|
| 小题5: | | A．radio | B．TV | C．robot | D．machine |
|
| 小题6: | | A．room | B．office | C．road | D．mobile phone |
|
| 小题7: | | A．parts | B．maps | C．video | D．music |
|
| 小题8: | | A．studio | B．teenager | C．bus | D．street |
|
| 小题9: | | A．five | B．four | C．three | D．two |
|
| 小题10: | | A．sender | B．receiver | C．Internet | D．system |
|
| 小题12: | | A．control | B．achieve | C．allow | D．imagine |
|
| 小题13: | | A．expensive | B．special | C．new | D．common |
|
| 小题14: | | A．cheaper | B．easier | C．more expensive | D．bigger |
|
| 小题15: | | A．computers | B．robots | C．satellites | D．watches |
|
