Choose the words on the answer form below which best fit the gaps in this text.Then click on the button on the answer page next to that word. If you change your mind, you can click another button.
Never get lost again!
You ..1.. probably never heard of NavStar, but you may have heard ..2.. the initials GPS. These two names are abbreviations. NavStar is the short form of the ..3.. clumsy words Navigation System using Time And Ranging, and GPS ..4.. for Global Positioning System. And they mean that in the ..5.. future, you will never get lost again.
NavStar is in ..6.. eighteen satellites which orbit the earth at an altitude of over 20 000 km. These satellites go around the world on different orbits, so that at ..7.. two of them are in the sky over every part of the Earth. This means that NavStar is somewhere overhead ..8.. you are reading this. These satellites transmit a radio signal. They are the most important ..9.. of the whole system, which is called GPS.
GPS as a ..10.. includes computers on the ground which calculate the time that it takes for the radio signals from NavStar to reach them. ..11.. this information, they can tell the people using the computers where they are. During the Gulf war, which was ..12.. in huge open spaces in the desert, GPS helped the allied armies to get to their targets faster than their enemies believed possible.
Today GPS is ..13.. by all sorts of businesses. Vehicles ..14.. with GPS allow their bases to know where they are at every minute of the day. GPS also works with map programmes on computers. Already some motorists use GPS to drive confidently to places they have never ..15.. to before.