Thelongerateenagerspendsusingelectronicdevicessuchascom...

問題詳情：

The longer a teenager spends using electronic devices such as computers and smart phones，the worse their sleep will be，a study of nearly 10，00016-to 19-year-olds suggests．

More than two hours of screen time after school was strongly linked to both delayed and shorter sleep．Almost all the teens from Norway said they used the devices shortly before going to bed．Many said they often got less than five hours sleep a night．

The teens were asked questions about their sleep routine on weekdays and at weekends，as well as how much screen time they clocked up outside school hours．On average，girls said they spent around five and a half hours a day watching TV or using computers，smart phones or other electronic devices．And boys spent slightly more time in front of a screen around six and a half hours a day on average．Playing computer games was more popular among the boys，whereas girls were more likely to spend their time chatting online!

Any type of screen use during the day and in the hour before bedtime appeared to disturb sleep—making it more difficult for teenagers to nod off．And the more hours they spent on these devices，the more disturbed their sleep became：When daytime screen use totaled four or more hours，teens had a 49％greater risk of taking longer than an hour to fall asleep．These teens also tended to get less than five hours of sleep per night．   

Dr．Hysing said her findings had suggestions for the wider population as so many people use these devices．“We know that sufficient sleep is essential for good physical and mental health．Logging off may be one important step toward securing a good night's sleep.”

Prof Russell Foster, an expert the University of Oxford,said，“This is an important study  as it provides practical evidence that the use of electronic devices before bed does indeed reduce sleep duration．”He said teenagers should be warned of this．

28．What is stressed in the first two paragraphs?

A．Teens now tend to have more problems with studies．

B．Teens get harder to fall asleep with more screen time．

C．Teens addicted to screen are likely to be more energetic．

D．Teens’ sleep duration has nothing to do with their screen time．

29．By asking questions，the study finds_________________.

A．boys are more likely to chat online than girls

B．girls are more frequent on the screen than boys

C．teens are attracted by different electronic devices

D．teens use the screen for the same purpose

30．What does the phrase “nod off” in the fourth paragraph mean?

A．shut off    B．get excited    C．focus on  D．fall asleep

31．How does Prof Russell Foster feel the study?

A．Beneficial  B．Uncaring     C．Doubtful  D．Dissatisfied

【回答】

BCDA

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