One day in a drawing class, the teacher told the class to draw an abstract (抽象的) drawing.
After a while, a small boy turned his drawing in. The teacher looked at it but saw nothing,
only a piece of paper.
“What did you draw?” said the teacher.
“A cow eats grass.” the boy answered.
“Where is the grass?”
“The cow has eaten it up.” replied the boy.
“Well, then, where is the cow?” the teacher asked again.
“It ate up the grass and went away to drink water.”