Questions 47 to 56 are based on the following passage.The popular notion that older people need less sleep than younger adults is a myth, scientists said yesterday. While elderly people （1）to sleep for fewer hours than they did when they were younger,this has a(n)（2）effect on their brain’s performance and they would benefit from getting more,according to research. Sean Drummond, a psychiatrist (心理医生) at the University of California, San Diego, said that older people are more likely to suffer from broken sleep, while younger people are better at sleeping （3）straight through the night. More sleep in old age, however, is （4） with better health, and most older people would feel better and more （5） if they slept for longer periods, he said. “The ability to sleep in one chunk (整块时间) overnight goes down as we age but the amount of sleep we need to （6） well does not change,” Dr Drummond told the American Association for the Advancement of Science conference in San Diego. “It’s（7） a myth that older people need less sleep. The more healthy an older adult is, the more they sleep like they did when they were （8） . Our data suggests that older adults would benefit from （9）to get as much sleep as they did in their 30s. That’s（10）from person to person, but the amount of sleep we had at 35 is probably the same amount we need at 75."A. alertB. associatedC. attractingD. clingE. continuingF. definitelyG. differentH. efficientlyI.formallyJ. functionK. mixedL. negativeM. sufficientN. tendO. younger 5（）