题目内容
阅读理解
Hundreds of years ago, travelers found their way by looking at the stars. They built towers that could be seen from far, made maps and invented the compass. Nowadays, almost every explorer and mountain climber uses the Global Positioning System (GPS,全球定位系统) to make their journeys safer. There are even plans to put GPS receivers on all the taxis in Beijing in time for the 2008 Olympics. Finding your way has never been so easy.
Technology has changed our lives:for less than 500 yuan, you can get a pocket-sized GPS gadget (小配件) that will tell you exactly where you are on Earth at any moment.
When people talk about a GPS, they usually mean a GPS receiver. The GPS is actually a set of 27 Earth-orbiting satellites—24 in operation and three extras in case one fails.
The US army developed this satellite network as a military navigation (导航) system in the 1970s, but opened it up to business use in the 1990s.
Each of the solar-powered satellites circles the globe twice every day. The orbits are arranged so that at any time, anywhere on Earth, there are at least four satellites “visible” in the sky.
A GPS receiver locates these satellites, records the distance to each, and uses the information to calculate the receiver's exact position on Earth.
A standard GPS receiver doesn't only identify (识别) your position on a map, but can also trace your path across the map as you move. If you leave your receiver switched on, it can stay in touch with the satellites to see how your location is changing.
Although it is based on a very simple idea, the contribution GPS has made to plane and sea travel, military operations and adventure sports means. It is one of the most revolutionary (革命性的) inventions of all time.
根据文章内容回答下列问题
1.How did travelers find their way hundreds of years ago? How many ways do you know from the passage?
2.Who first developed GPS satellite network?
3.How much do you need to pay for a pocket-sized GPS gadget?
4.What do people mean when they talk about a GPS?
5.What can a standard GPS receiver do?
解析:
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1.By looking at the stars, building towers, making maps and inventing the compass. There are 4 ways. 2.The U. S. army. 3.Less than 500 yuan. 4.A GPS receiver. 5.It can identify your position on a map and also can trace your path across the map as you move. |
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