9．
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."
