20.
World Sleep Day is March 21.Many experts have held a press conference (新聞發(fā)布會) in Beijing Hotel.Sleep is sometimes called"the cousin of death".But funnily enough,it is also one of the most important things we need to stay alive.People spend almost a third of their lives doing one things:sleeping.Sleep is like food for the brain.Enough sleep helps the body and brain grow and develop.
People of different ages need different amounts (數(shù)量) of sleep.According to the National Sleep Foundation in the US,adults need seven to nine hours of sleep every night.For students aged 10to 17,a healthy amount is about eight to nine hours per night.However,many students don't get enough sleep because of early school start times and too much homework.The China Youth and Children Research Center reported that about 80% of middle school students don't get enough sleep.Students without enough sleep may get poor grades.They can't pay attention in class or do well in sports.
To solve this problem,scientists advise that students should get less schoolwork and more time to sleep.There are some other ways to help people get enough sleep,such as taking a 20-minutes nap (小睡) during the day.Good sleep habits are also helpful.For example,try to go to sleep and wake up at the same time every day,even on weekends and during holidays.
51.How much sleep do adults need per night?A
A.7~9hours.
B.8~10hours.
C.More than 10hours.
D.Less than 7hours.
52.Why don't many students get enough sleep?C
A.Because they always stay up late and get up late.
B.Because they naturally wake up early and they have too much housework.
C.Because they have too much homework and their school starts too early.
D.Because they go to bed and wake up at the same time.
53.What may happen if teens do not get enough sleep?B
A.They may do well in sports.
B.They may not do well in their studies.
C.They will not finish their homework.
D.Their bodies and brains may grow better.
54.Which is NOT a reason that so many students don't get enough sleep?A
A.They have too many exciting classes in the day.
B.They have too much homework to do.
C.They may have sleeping problems.
D.They have to get up very early to go to school.
55.Which of the following is NOT a way of helping people get enough sleep?D
A.Getting up at the same time every day.
B.Take a 20-minute nap during the day.
C.Having good sleep habits.
D.Take sleeping pills before going to sleep.