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 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 as we need at 75."

　　[A] alert

　　[B] associated

　　[C] attracting

　　[D] cling

　　[E] continuing

　　[F] definitely

　　[G] different

　　[H] efficiently

　　[I] formally

　　[J] function

　　[K] mixed

　　[L] negative

　　[M] sufficient

　　[N] tend

　　[O] younger

　　答案解析：

　　文章大意：本文主要讲述的是关于老年人睡眠的问题：是否老年人与年轻人相比只需要较少的睡眠时间?

　　1. N tend tend to 固定搭配;表示"倾向于;"符合句意;

　　2. L negative 空格后是effect， 前面是a(n)， 由此可见，该处需要填入一个形容词;题目给出的形容词有negative, sufficient, younger;根据前后语意，填入negative最为恰当，表示"少的睡眠时间对大脑的活动有负面的影响。"

　　3. H efficiently 根据推测，该处应该填入一个副词，题目给出的副词有efficiently, definitely, formally;前面提到，老年人在睡觉的时候更容易被打断，而后面用while提出一个对比的概念，年轻人相比起来能获得更_______ 的睡眠;综合起来，选用efficiently(最有效率的)最为准确。

　　4. B associated be associated with 固定搭配;表示"与…联系在一起";本句话表示"更多的睡眠通常都与健康度联系在一起";

　　5. A alert 先看整句话的含义，"如果他们能睡更长的时间，他们的感觉应该会更好以及…"那么，该处应该填入一个褒义词，选择alert比较恰当，表示"更加警觉，机灵";

　　6. J function 根据判断，此处应该填入一个动词，剩下的动词有cling, function;整句话的意思是"当我们上了年纪的时候，我们一觉睡到天亮的能力下降了，但是，我们需要…的睡眠量并没有改变;"空格后的单词是 well， cling 在这里并不合适，一般与to连用;选用function 最为适合;

　　7. F definitely 作者在首段已经提出这个观点是一个myth，那么显而易见最后一段中出现的myth是作为一种强调手段，应填入definitely;

　　8. O younger 空格的前面是 when they were…， "当他们年轻的时候";应填入younger;

　　9. E continuing 本句的意思是"我们的数据显示老年人将从…获益;"空格的后面是"得到和他们在三十多岁的时候能得到的睡眠一样多";根据上下文意思，该处应填入"continuing";

　　10. G different different from 固定搭配;表示"和…不同"。