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阅读下列四篇短文，从每小题后所给的A,B,C或D四个选项中，选出最佳选项。 Kingda Ka, the tallest roller coaster （过山车） on Earth, drops its passengers a life-flashing 418 feet. Ferrari World's Formula Rossa, the fastest, takes riders' breath away at speeds of up to150 mph. BRC Imagination Arts, a Southern California design firm, has proposed something entirely new: a ride that creates the sensation of zero gravity for up to eight seconds at a time. BRC drew its concept from the "Vomit Comet," the plane NASA uses to train astronauts. Its proposed theme-park ride would travel up and then back, similar to the existing "Superman: Escape from Krypton" coaster at Six Flags Magic Mountain in California. But unlike Superman and other open-car coasters, the vomit-comet ride would be fully enclosed. Riders would enjoy the illusion of floating within a stable chamber. To create that illusion, a special motor system would speed coasters up the track with great precision（精确度）. As the coaster approached a top speed of more than 100 mph, it would suddenly and ever so slightly slow down—just enough to throw the passengers up from their seats and then quickly adjust its speed to fly in formation with and around the passengers. As the coaster reached the top of the track and began to drop back down, the computer system would continue to match its speed to that of the falling passengers, extending the sensation of weightlessness for several additional seconds, and finally rapidly slow down to a stop back at the base station. | 
