Here is a story about a vet (兽医) and a farmer. The vet
lived in a small town. On a cold winter night, he heard a knock (敲) on the door.
He opened the door, and saw the farmer. "Can you go to my place
right away, Vet It’s very important," the farmer asked. "All
right, if you give me a few minutes to get ready," the vet answered.
The farmer waited. And then, when the vet was ready, he said to him, "Is
it OK if I sit in your ear" "Certainly. Jump in!" The vet
said. He started the ear and they were off. When they arrived
at the farmer’s house on the other side of the hills. The vet asked, "Is it one
of your cows again" "No, it’s not. It’s just that I need a
ride home," answered the farmer. Then he handed the vet five dollars and said,
"Here you are. The taxi driver in town wanted seven dollars to drive out here,
and I know you only charged (收费) five dollars, if you didn’t have to do much
work." The farmer didn’t know the vet.