急求一篇关于狗的生物英语短文

Dogs

You may have a dog for a pet at your house. Maybe you have some friends who have dogs.

No one knows how many millions of people in the world have dogs for pets. More than 1 million new purebred dogs get registered (signed up) with the American Kennel Club (AKC) each year. The AKC is the main organization for purebred dogs in the United States. A purebred is a dog whose parents and ancestors all came from the same breed of dog. A dog of mixed breeds is sometimes called a mongrel or a mutt.

WHAT ARE THE MAIN KINDS OF DOGS?

Beginning hundreds of years ago, breeders mated male and female dogs that had certain qualities, or traits. They wanted the puppies to have the same traits as the parents. Dogs that developed these traits were called breeds.

The AKC recognizes about 150 breeds. It puts these breeds into seven groups called terrier, working, sporting, hound, herding, toy, and nonsporting dogs.

Terriers have stiff,