Dog——A Friend of Man胡迪

Dogs are friends of man.They work for us.They hunt with us.They also play with us.But a long time ago,in all over the world,dogs were wild.Dogs can go back to the Stone Age.All dogs had the same ancestor (祖先).It is believed that this ancestor was much like a wolf.Other animals,like fox,also came from this ancestor.Thousands of years ago,man began to tame (使驯服) the wild dogs.When the dogs were tamed,they were trained