题目

阅读理解 Screen time before bedtime may leave people feeling sleepy in the morning. Cell phones, computers and TVs emit (发出) blue light. And exposure to that bluish light during the two hours before bed can keep us from getting a good night's rest, a new study finds. It cuts down on the length of people's sleep. It also leaves them feeling tired in the morning and can disrupt the body clock. Data shows that this blue light tends to make us more alert at night, making it harder to get all the rest we need. Green and his team surveyed 19 people — all in their 20s — for a sleep study. All spent two hours on a computer right before bedtime. But they didn't all experience the same light exposure. Looking at screens that gave off intense blue light cut someone's sleep by about 16 minutes, compared to when they had used screens with red light. Those exposed to blue light also woke up more often at night than if they had been exposed to red light. "The normal blue light emissions from the computer screen also affect how much melatonin (褪黑素) each volunteer makes. It is released into our blood around 9 p. m. When our bodies make less melatonin, we may still feel too alert at bedtime to fall asleep when the body is tired. And body temperature won't drop as expected after we use devices emitting lots of blue light. Using screens before bed damages the body's biological clock," Green says. "More and more kids are using screens nowadays. Sleep is important, especially during the first few years of life when 'neural plasticity' (神经可塑性) is at its greatest. Their brains are still developing the ability to learn and pay attention. That makes the new results worrisome," Green says. Rahman says that the new work makes a good point about how blue light from screens can be bad for our bodies. However, he points out, the light in this study is extremely bright. It is far brighter than what a normal computer, tablet or TV will emit. Still, Rahman says the results remind us to think about how we should use screens before bed. （1） The blue light from the screens may cause people to ________. A . tend to work at night B . get attentive in the morning C . be less sleepy before bed time D . be affected less by the body clock （2） What is Paragraph 2 mainly about? A . People's concern about light exposure. B . A study on blue light's effects on sleep. C . Reasons for blue light's effects on sleep. D . Effects of various types of light on sleep. （3） What can be implied from Green's remarks? A . Melatonin may affect people's neural plasticity. B . Blue light may affect children's brain development. C . Exposure to normal screen has little impact on sleep. D . The low temperature of body helps produce melatonin. （4） What's Rahman's possible attitude towards the Green's study? A . Uncaring. B . Approving. C . Objective. D . Critical. 答案： C B B C

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