阅读理解 Dogs are friends of man. They work for us. They hunt (狩猎) with us. They play with us. But once, all over the world, dogs are wild (野生的). Dogs go back to the Stoen Age. All dogs had the s ame ancestor(祖先). It is believed that this ancestor was much l ike a wolf (狼). Other animals like the fox, came from this ancestor, too. Thousands of years ago, man began to tame (驯服)the wild dogs . When the dogs were tame, they were trained (训练). The strong dogs became working animals . They were trained to pull heavy loads (担子). They learned to keep watch over the sheep and other animals. Working dogs had other jobs, too. Some dogs were not strong. But they could help man hunt for . Other dogs were best as pets. At first , there were only a few kinds of dogs. Today there are more than 100 kinds. (     )1. The word in the story that means an animal far bac k in another animal's family is ancestor. (     )2. The story make us believe that Man has helped change animals. (     )3. The strong dogs turned into foxes. (     )4. Dogs are pets from the beginning. (     )5. Dogs and man have been friends for a long time.