It is 7 am and the alarm is going off.You know you have to be out of bed to catch the school bus.But the desire to stay in the bed is so strong.You believe that your body is fixed in the bed.
During adolescence （青春期），the body goes through many changes，which includes a change in sleep patterns.According to researchers，this is because of a hormone （荷爾蒙） called melatonin that is secreted （分泌） by the pineal gland — a tiny structure deep inside the brain.Melatonin is very important.It can control the body's natural day-night rhythm and cause a person to become sleepy by lowering his or her body's core temperature.
In teens，melatonin is secreted much later in the evening and continues to increase throughout the night.This makes it difficult for teens to fall asleep early as they did in their younger years.Likewise，the effect of melatonin continues until much later in the morning，making it hard for them to wake up early.
An American National Sleep Foundation study found that at least one in four teens are tired and fall asleep in school at least once a week.Sleep is food for the brain.During sleep，important body functions and brain activities happen.Staying up late can be harmful and even deadly — especially for those who drive.A slow brain makes it difficult to focus and can hurt grades at school.Since sleep-deprived （睡眠不足的） children tend to eat more carbs （碳水化合物），they are more likely to suffer from depression.
The American Association of Pediatrics （AAP） recommends that middle and high schools should start later — not before 8：30 am.This should give teens some more time to sleep in and eat breakfjye.ait.As a result，their brains can receive new information in a more efficient manner.In fact，AAP suggests that letting teens sleep in late during school days can lead to overall benefits for teens.However，starting school later means a later end time too.Will that affect afterschool activities？
（1）What does the underlined word "this" in Paragraph 2 refer to？ BB
A．The students fall asleep early.
B．The shifts of the sleeping patterns.
C．The pineal gland secretes melatonin.
D．The adolescents wake up early.
（2）What does the second paragraph mainly tell us about melatonin？ CC
A．Its formation.
B．Its temperature.
C．Its role.
D．Its potential.
（3）What do we know about teenagers' sleep？ AA
A．The length of sleep can influence teenagers' brain health.
B．The early secretion of melatonin makes teenagers sleep late.
C．The most of teenagers in America always go to sleep late.
D．The late secretion of melatonin makes teenagers pay more attention in class.
（4）What will happen if schools accept AAP's suggestion？ BB
A．Students will eat more carbs.
B．Students will learn better and faster.
C．Students will get up earlier than before.
D．Students will have more afterschool activities.
【答案】B；C；A；B
【解答】
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發(fā)布：2024/5/27 14:0:0組卷：6引用：1難度：0.4
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