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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(生物学上)these sleepyhead(贪睡者)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(方式).
　　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 night and sleep later in the morning. But it’s not just a matter of choice---their bodies are going through a change of sleep patterns.
　　All of this makes the transfer(迁移)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, adolescents are up against difficulties when they try to be up by 5 or 6 a.m. for a 7:30 a.m. first bell. 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 bedtime

B．it is biologically difficult for students to rise early

C．students work so late at night that they can’t get up early

D．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 around

B．agree with others

C．fall asleep

D．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 health care.

B．Problems in adolescent learning.

C．Adolescent sleep difficulties.

D．Changes in adolescent sleep needs and patterns.

An Australian researcher is urging parents to load up their teenager’s backpack and make them walk to school.
Professor Leon Straker says students who walk or cycle to school are less likely to have back and neck pain. But the study of 1,202 Western Australian 14­year­old found that 72% of students travelled to school by car or bus. Straker says the study suggests walking or cycling while carrying a schoolbag helps improve trunk (躯干) and spinal (脊柱的) muscle strength.
This helps reduce back pain because greater muscle strength improves support for the back during load carrying .Despite advocating that parents get their children moving，Straker warns bag load should not exceed (超过) 15% of body weight.
Straker says the study also stresses that neck pain is as common as back pain among young teenagers. This is an area that has been largely ignored，he says，but can be an important indicator of neck pain into adulthood.
For the study，students were asked a series of questions such as how long they carried their bags for，how they carried their schoolbags，the method of travel，and their perceptions(感觉) about the bag’s weight.
Straker says about half of all participants experienced back and neck pain，with slightly more females reporting neck pain. However，the gender (性别) difference may also be due to the fact that females have lower pain tolerance.
Studies from the 1980s found carrying a bag over one shoulder was most common among teenagers. However in this study 85% of participants carried their bag over both shoulders.
Straker believes the change has been driven partly through education campaigns，but also by increasing fashion status of backpacks and improved design.
小题1:In the opinion of Leon Straker，parents should________.

A．reduce the load of their children’s schoolbags

B．put more books in their children’s schoolbags

C．get their children’s schoolbags ready for school

D．ask their children to walk to school carrying schoolbags

小题2:If a child weighs 40 kilograms，the weight of his schoolbag should be________.

A．no more than 15 kg

B．less than 6 kg

C．as heavy as 9 kg

D．more than 6 kg

小题3:We can learn from the passage that________.

A．most of the students in Australia walk to school

B．neck pain is uncommon among young teenagers

C．walking while carrying a backpack helps reduce back pain

D．males are more likely to experience back pain than females

小题4:According to the passage，what change has taken place since the 1980s?

A．How students carry their schoolbags.

B．How heavy students’ schoolbags are.

C．How students go to school every day.

D．How long students carry their schoolbags for.

Martin Cooper , a US researcher , was considered _______ the first cell phone .

A．invented

B．to invent

C．having invented

D．to have invented