[简答题]Surveys have shown that most football and basketball injuries involve the knee, either through twisting or through application of lateral force. Surgery for such injuries has become much simpler with the invention of a thin device containing a fiber optics light that can be inserted into a thin slit in the knee. Repair can be accomplished through this narrow opening. Long-distance runners also suffer knee injuries, but a more common problem for runners is stress fracture, which is a weakening of the front of the shinbone caused by overuse, with pain and possible bone cracking as the result. Ligament tears are more common in gymnastics. Almost all these conditions heal with rest. Prevention of injuries depends primarily on good conditioning. Athletes are also protected by the use of better padding materials and of face masks and eye protectors in rough sports.
The improper or illegal use of drugs and substances for the temporary improvement of athletic performance in competitions h

[简答题]Surveys have shown that most football and basketball injuries involve the knee, either through twisting or through application of lateral force. Surgery for such injuries has become much simpler with the invention of a thin device containing a fiber optics light that can be inserted into a thin slit in the knee. Repair can be accomplished through this narrow opening. Long-distance runners also suffer knee injuries, but a more common problem for runners is stress fracture, which is a weakening of the front of the shinbone caused by overuse, with pain and possible bone cracking as the result. Ligament tears are more common in gymnastics. Almost all these conditions heal with rest. Prevention of injuries depends primarily on good conditioning. Athletes are also protected by the use of better padding materials and of face masks and eye protectors in rough sports.
The improper or illegal use of drugs and substances for the temporary improvement of athletic performance in competitions h

[单项选择]Judging from recent surveys, most experts in sleep behavior agree that there is virtually an epidemic of sleepiness in the nation. "I can"t think of a single study that hasn"t found Americans getting【C1】______sleep than they ought to." says Dr. David. 【C2】______people who think they are sleeping enough would probably be【C3】______with more rest. The beginning of our sleep deficit crisis can be【C4】______to the invention of the light bulb a century ago. From diary entries and other personal【C5】______from the 18th and 19th centuries, sleep scientists have reached the【C6】______that the average person used to sleep about 9.5 hours a night. "The best sleep habits once were【C7】______on us, when we had nothing to do in the evening down on the farm, and it was dark." By the 1950s and 1960s, that sleep schedule had been reduced【C8】______, to between 7.5 and 8 hours, and most people had to wake to an alarm clock. "People cheat on their sleep, and they don"t even【C9】______they"re doing it," says Dr. David. "They think they"re okay because they can【C10】______on 6.5 hours, when they really need 7.5, 8 or even more to feel ideally【C11】______." Perhaps the most merciless robber of sleep, researchers say, is the【C12】______of the day. Whenever pressures from work, family, friends and community【C13】______, many people consider sleep the least【C14】______item on the agenda. "In our society, you"re considered【C15】______if you say you only need 5.5 hours" sleep. If you say you"ve got to get 8.5 hours, people think you lack【C16】______and ambition." To assess the【C17】______of sleep deficit, researchers have put subjects【C18】______a set of psychological and performance tests requiring them, for instance, to add columns of numbers or recall a passage read to them only minutes earlier. "We"ve found that if you"re sleep-deprived, performance【C19】______," says Dr. David. "Short-term memory is impaired,【C20】______are abilities to make decisions and to concentrate."【C6】
A. effect
B. summary
C. conclusion
D. concept