题目内容
Today, there are more than 100 kinds of dogs in the world. Many people like to have dogs as their pets. Dogs are friends of man because they are lovely and they are faithful(忠诚的) to their masters.
Dogs can do a lot of work for man. They play with us. They hunt with us. They also keep door for us. But long ago，dogs all over the world were wild（野生的）.
All dogs have the same ancestor（祖先）．People believe that a dog's ancestor may be a wolf .Other animals, such as the fox, came from this ancestor, too. Millions of years ago, man began to feed and train wild dogs. The strong dogs became working animals.Working dogs had many kinds of jobs. They could help people to pull heavy things. They learned to keep an eye on the sheep and other small animals. They could help people in the war（战争). Some dogs were not strong. But they could help man hunt. Other dogs were the best as pets.
根据短文内容，回答下列问题。（NO MORE THAN 5 WORDS)
1.How many kinds of dogs are there in the word?
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2.Why do people like dogs?
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3.Whose ancestor may be a wolf according to the passage?
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4.When did man begin to feed and train wild animals？
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5.What kind of dogs can be working dogs?
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