ＣA Brown University sleep researcher has some advice for people who run high schools: Don’

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A Brown University sleep researcher has some advice for people who run high schools: Don’t start classes so early in the morning. It may not be that the students who nod off at their desks are lazy. And it may not be that their parents have failed to enforce (确保) bedtime. Instead, it may be that biologically these sleepyhead students aren’t used to the early hour.
“Maybe these kids are being asked to rise at the wrong time for their bodies,” says Mary Carskadon, a professor looking at problem of adolescent (青春期的) sleep at Brown’s School of Medicine.
Carskadon is trying to understand more about the effects of early school time in adolescents. And, at a more basic level. she and her team are trying to learn more about how the biological changes of adolescence affect sleep needs and patterns.
Carskadon says her work suggests that adolescents may need more sleep than they did at childhood, no less, as commonly thought.
Sleep patterns change during adolescence, as any parent of an adolescent can prove. Most adolescents prefer to stay up later at nigh and sleep later in the morning. But it’s not just a matter of choice –their bodies are going through a change of sleep patters.
All of this makes the transfer from middle school to high school—which may start one hour earlier in the morning ---- all the more difficult , Carskadon says. With their increased need for sleep and their biological clocks set on the “sleep late, rise late” pattern, adolescent are up against difficulties when it conics to trying to be up by 5 or 6 a.m. for a 7:30 a.m. first hell. A short sleep on a desktop may be their body’s way of saying. “I need a timeout.”
【小题1】Carskadon suggests that high schools should not start classes so early in the morning because .A．it is really tough for parents to enforce bedtimeB．it is biologically difficult for students to rise earlyC．students work so late at night that they can’t get up earlyD．students are so lazy that they don’t like to go to school early【小题2】The underlined phrase “nod off” most probably means “ ”.A．turn aroundB．agree with othersC．fall asleepD．refuse to work【小题3】What might be a reason for the hard transfer from middle school to high school?A．Adolescents depend more on their parents.B．Adolescents have to choose their sleep patterns.C．Adolescents sleep better than they did at childhood.D．Adolescents need more sleep than they used to.【小题4】What is the test mainly about?A．Adolescent heath care.B．Problems in adolescent learning.C．Adolescent sleep difficulties.D．Changes in adolescent sleep needs and patterns.B

(答案→)B 解析：该文是关于中学生睡眠问题的科学研究成果，难度适中，且有一定梯度。【小题1】根据第一段最后一句话“Instead, it may be that biologically these sleepyhead students aren’t used to the early hour.” 推断出。【小题2】此题考查考生猜词的能力。青少年太早来到学校上课，就坐在桌旁打盹。而且我们知道“nod”有点头的意思。根据常识，打盹的时候会情不自禁地垂下头。【小题3】本题属于推理判断题,考查考生对语篇的整体理解程度.其实本题难度不大,,其它三个选择项比较容易排除.【小题4】考查对文章大意的理解。A项范围太广。B项青少年的学习问题。C青少年的睡眠困难，而文章讲得是青少年睡眠时间不足，甚至课堂上都要打盹，与文章内容不符。

就是这个解释