[originaltext] The Global Positioning System (GPS) has become indispensable

游客2023-12-25  13

问题  
The Global Positioning System (GPS) has become indispensable for soldiers, pilots, hikers, yachtsmen, even bankers, ever since the U.S. Department of Defense started filling the sky with satellites about 25 years ago, in order to improve navigation for fighters, bombers and warships. More recently, GPS has allowed the development of precision-guided weapons, the smart bombs that home in on targets: between Serbia four years ago and this year’s Iraq war, the proportion of such bombs used rose from no more than 3 percent to at least 60 percent.
    However, the GPS is also an essential prop to countless civil applications; for every military user, there are now 100 civilian users. It provides not only satellite-navigator systems in cars and boats; it is used by Internet service providers, by banks and by surveyors. One day it might be used by air traffic control systems to permit "free flight", in which pilots of commercial aircraft find their own route and stay clear of other aircraft, without the cumbersome business of radio telephone contact with controllers on the ground.

选项 A、Commercial aircraft is guided by GPS.
B、Civilian aircraft are free to move over all territories.
C、Cargo carriers no longer collide with one another.
D、Passenger flights are safe to fly with military aircrafts.

答案 B

解析 原文最后部分讲解了什么是“free flight”,其中“pilots of commercial aircraft find their own route”可对应选项a的内容;“stay clear of other aircraft”可与选项c中“no longer collide with one another”对应,并且由上述两点还可推断出选项d的内容是正确的。那么只有选项b的说法与原文不符,因此该选项是正确答案。
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