靖在第_____处填上正确答案。
A. space
B. locations
C. instructions
D. time
In the third paragraph the author wants to tell the reader that_________．
A. it is natural for teenagers to stay up late and get up late
B. staying up late has a bad effect on teenagers’ability to think and learn
C. during puberty most teenagers experience a kind of gray cloud
D. it is hard for teenagers to get out of bed in the morning
靖在第_____处填上正确答案。
A. another
B. other
C. each other
D. one another
What is implied in the second paragraph？
A. Young children’s biological clock has the same rhythm with that of the teenagers．
B. People after puberty begin to go to bed earlier due to the change of the biological clock．
Children before puberty tend to fall asleep earlier at night than adolescents．
D. Teenagers go to bed later than they used to due to the light from the computer screen．
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