Answer the questions（根据短文内容回答下列问题）

The domestic dog is one of the world's most popular pets. There are over 150 breeds, or types, of dogs. Most scientists agree that dogs evolved from wolves-about 15,000 years ago.

Many of the dog breeds we know today evolved over the years. Some became shorter and heavier. Some gradually had longer or shorter fur. Many of these changes happened naturally. However, many breeds came about because people purposely bred them to do different jobs.

Poodles Because poodles often have fancy haircuts, many people think of them as the “supermodels” of the dog world. However, poodles are really working dogs. They are strong and smart, and they are good swimmers and hunters. Poodles often work as guard dogs, too.

Jack Russell Terriers Jack Russell Terriers are small dogs. However, they are one of the hardest working breeds. Many Jack Russell Terriers today are pets. But a hundred years ago, these dogs had an important job: to keep rats and mice off farms.

Italian Greyhounds The Italian Greyhound is an old dog breed. These dogs were popular with kings and queens in Europe over 500 years ago. Do you know why? With no electricity, the castles of Europe were very cold. People used Italian greyhounds to warm their beds before they went to sleep.

【小题1】Dog breeds never change, do they?
【小题2】When did wolves turn into dogs?
【小题3】According to the article, which dog is good at swimming?
【小题4】Why did farmers a hundred years ago like Jack Russell Terriers?
【小题5】Why were the castles in old days very cold?
【小题6】Which of the three dogs would you like as a pet? Give your point and reason(s)