The New York Times states that cheerleading（啦啦队） is the fast growing girl’s sport, yet more than half of Americans do not believe it is a sport. For them, cheerleading is just leading cheers. If the girls are doing dances on the sidelines（球场边） or they’re holding a sign trying to get a crowd response, that technically would’t be considered a sport. While sideline cheerleaders’ main goal is to entertain the crowd and lead them with team cheers, the competitive cheerleaders are playing to win. A sport, according to the Association of Cheerleading Coaches and Advisers, is a physical activity or competition against or with an opponent（对手）, governed by rules and conditions under which a winner is declared, and the primary purpose of the competition is a comparison of the relative skills of the participants. Because competitive cheerleading follows these guidelines, it is a sport. Competitive cheerleading includes lots of physical activities. Like gymnasts（体操运动员）, cheerleaders must learn to tumble（翻跟头）. They perform standing back flips（蹦跳）, round flip flops, and full layout twists. Cheerleaders also perform lifts and tosses. This is where the fliers are thrown in the air, held by bases in different positions that require strength and cooperation with other teammates. Just as basketball and football have guidelines for competitive play, so does competitive cheerleading. The whole routine has to be completed in less than 3 minutes and 15 seconds and the cheerleaders are required to stay within a certain area. Competitive cheerleaders’ goal is to be the best. Just like gymnasts, they are awarded points for difficulty, technique, creativity and sharpness. The more difficult a stunt（绝技）, the sharper and more in-sync（同步的）, the higher score they can get. Cheerleading is a team sport so without cooperation and synchronization（同步）, first place is out of reachAccording to the passage,（）cheerleading is a sport

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A．fast-growing B.B．sideline C.C．competitive D.D．physical