A farmer had some puppies to sell. He painted a sign advertising them on the edge of his yard.One day, a little boy came to buy one of the puppies. With a whistle(口哨), the farmer called, “Here, Dolly!” Out from the doghouse ran Dolly followed by four little balls of fur. The little boy stood against the fence. His eyes danced with delight.
As the dogs made their way to the fence, the little boy noticed something else inside the doghouse. Slowly another little ball appeared, something wrong with its legs, doing its best to catch up.“I want that one,” the little boy said.
The farmer knelt down at the boy's side and said, “Son, you don't want that puppy. He will never be able to run and play with you like these other dogs would.”
With that, the little boy stepped back from the fence, reached down and began rolling up one leg of his trousers. In doing so, he showed a steel brace(固定器) running down both sides of his leg attaching itself to a specially made shoe. Looking back up at the farmer, he said, “You see, sir,  I don’t run too well myself, and he will need someone who understands.”
How did the farmer advertise his puppies?

A．Advertise them in the newspaper.

B．Put up a sign in his yard.

C．Show them to his neighbors.

D．Send pictures to a magazine.

The underlined words “four little balls of fur” refer to “______”.

A．four toy balls	B．four balls made of fur
C．four lovely dogs	D．four puppies with no fur

Why did the boy choose the last dog?

A．Because they have something in common.

B．Because he didn't have enough money.

C．Because it was the most lovely one.

D．Because the farmer wouldn't sell other dogs.

According to the story, we know that the boy .

A．didn't like dogs at all	B．needed a dog to help him
C．could run as fast as others	D．had an artificial(假的) leg