阅读短文，根据内容填空。
An art teacher asks his students to draw pictures. They can draw anything (无论什么东西) they want.
After a while, a boy hands in (上交) his picture. The teacher looks at it but sees nothing (没有什么东西) on the paper.
“What do you draw?” the teacher asks.
“A cow eats grass.” the boy answers.
“But where is the grass?” the teacher asks again.
“The cow has eaten it up.” answers the boy.
“Where is the cow?”
“When it eats up the grass, it feels thirsty and goes to drink water.”
【小题1】The teacher asks his
______ to draw anything they want.
【小题2】The teacher looks at the boy’s picture, but sees
______ on the paper.
【小题3】The boy says, “The
______ eats the grass up.”
【小题4】The teacher can’t see a cow or any
______ on the paper.
【小题5】The boy says, “The cow eats up the grass, then it goes to drink
______.”
