共享题干题 (三)Please Fasten Your Seatbelt根据下列材料，请回答下列问题。 Severe turbulence (潮流 can kill aircraft passengers. Now, in test flights over the Rocky Mountains, NASA (美国航空航天局)engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it. Clear-air turbulence often catches pilots by surprise. Invisible to radar, it is difficult to fore- cast and can hurl (用力抛出去) passengers about the cabin. In December 1997, one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds. However, passengers can avoid serious injury by fastening their seatbelts. "It is the only antidote (对策)for this sort of thing," says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards, California. The centre's new turbulence detector is based on lidar, or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect. The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air, the speed equals the plane's airspeed. But as the particles swirl (打漩) in rough air, their speed of approach increases or decreases rapidly. The rate of change in speed corresponds to the severity (激烈程度)of the turbulence. In a series of tests that began last month, a research jet flew repeatedly into disturbed air over the mountain ridges (山脉) near Pueblo, Colorado. The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered. Bogue says that he had "a fortable amount of time" to fasten his seatbelt. The researchers are planning to improve the lidar's range with a more powerful beam. The system could be installed on mercial aircraft in the next few years.1.[不定向选择题]In December 1997, a United Airlines flight hit unexpected rough air,_________A.causing a lot of damage to the plane B.throwing its passengers out of the cabin C.resulting in heavy casualties D.forcing the pilot to make an emergency landing 2.[不定向选择题]The last paragraph tells us, among other things, that_________A.the lidar detector needs improvement B.many airlines are interested in the system C.passengers often forget to fasten their seatbelts. D.the lidar detector can be used in a wide range of areas.
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1.参考答案：C
参考解析：该题问的是1997年12月联合航空公司的一架班机在碰到这种气流后，遭遇了什么结果?原文讲到造成一人死亡，多人受伤，据此判断，损失惨重，故选C。
2.参考答案：A
参考解析：A此题是根据最后一段的第二句“There searchers are planning to improve the lidar's range with a more powerful beam．”出的题，这句的意思是说，研究人员正计划采用功能更强大的光束来提高雷达的测定范围。据此可以判断，雷达尚需改进，故A为正确答案。3.[不定向选择题]We can infer from the fifth paragraph that_________A.the lidar detector can successfully forecast turbulence B.researchers are not sure about the effectiveness of the lidar detector C.passenger planes will be used in further experiments. D.no more test flights are needed