根据短文内容从各题的四个选项中选择一个最佳答案，回答第56-70题，并将代表字母填在答题卡的相应位置。（每小题1分，共15分）
During the day we work and play, and at night we sleep. Our bodies rest while we are sleeping. In the morning we are ready to work and play again. When we are asleep, our bodies grow（生长）most. When children feel tired and angry, they usually need more sleep. We can get our lessons better, and we feel better, too, when we have enough sleep. Boys and girls, eight or nine years old, need ten hours of sleep every night. Our bodies need plenty of （大量的）air when we sleep. If we do not get enough fresh air we wake up feeling tired. While in bed we must not cover our heads. If we do, our lungs（肺）will not get enough fresh air. If we open our windows at night we can have plenty of fresh air. Cool air is better than warm air. Boys and girls must get plenty of sleep if they want to grow and be strong.
Our bodies grow most while we are ______.

A．eating	B．playing
C．sleeping	D．exercising

Which is the best air for us? ______ air.

A．Hot

B．Cool

C．Warm

D．Dry

What often makes us feel tired in the morning?

A．Too much air.	B．Not enough fresh air.
C．Too much cold air.	D．Too much sleep.

How can you get enough fresh air at night? You can ______.

A．open your windows	B．not sleep in bed
C．sleep ten hours	D．cover your head

The writer is trying to tell boys and girls ______.

A．to get their lessons better

B．not to cover their heads

C．how to go to bed

D．to get enough sleep