阅读理解（5分）：

　During the day we work and play, at night we sleep. Our body rests while we sleep. In the morning we are ready to work and play again. Our body grows most while we are asleep. Children usually need more sleep. We can learn our lessons better, after we have had plenty of rest. Boys and girls who are eight or nine years old need ten hours of sleep every night. Our body needs plenty of air when we sleep. If we do not get enough fresh air, we will feel tired when we wake up. While in bed we must not cover our head. Our lung（肺）needs to get enough fresh air. If we open our windows at eight, we can have plenty of fresh air. Cool air is better than warm air. Boys and girls who want to be strong must get plenty of sleep.

1． Our body grows most while we are ________.

[　　]

A．eating　　　　　　B．playing

C．sleeping　　　　　D．exercising

2． Too little sleep makes us ________.

[　　]

A．tired　　　　　　B．hungry

C．happy　　　　　 D．grow

3． What may cause（引起）us to feel tired in the morning? ________.

[　　]

A． Too much air　　　　　B． Not enough fresh air

C．Too much cold air　　　 D．too much sleep

4． What does the lung need most?

[　　]

A． Fresh air　　　　　　B． Covering

C． Warm air　　　　　　D． Exercise

5． In order to get plenty of fresh air at night, you should________.

[　　]

A． not cover your head　　 　  B．play outdoors

C． sleep outside　　　    　　D． sleep ten hours