阅读理解。 In Texas, there was once a prairie dog town that housed about 400 million of the small,fat rodents (啮齿动物) in its network of tunnels and burrows (穴). But it was not crowded in this town. There was sunlight and fresh air for all. There was enough grass to furnish food. Scientists have leamed that the prairie dogs found in many parts of the West can live together in huge numbers without being crowded. Scientists know that each prairie dog town is divided into separate territories. Each section belongs to a family group,or clan. The animals cooperate in many ways. One of the prairie dogs who sense danger will wam the others. All the animals take cover. Still,the animals stay within their own sections of the town and eat only the plants that grow there. Young prairie dogs are taught the clan boundaries,and they later teach the boundaries to their own young. What happens when one clan becomes too large for the food in its territory? Is there any war with the next-door clan to win more land? Not at all. The territory is turned over to the younger members of the clan. The older animals move out to the edge of the town. They stake out a new territory and dig a new network of tunnels. Before long, another clan will form a new territory beyond them. In this way, a prairie dog town grows and grows,but the number of animals in each section stays about the same. 1. What does the underlined word'furnish' mean in Paragraph 1? A. grow B. provide C. cook D. furniture 2. In what way do the prairie dogs live together? A. They live in a small but cooperative family. B. They live in a crowded and cooperative family. C. They live in a big but united family. D. They live in a large family without cooperation. 3. Young prairie dogs are taught the clan boundaries. The most probable reason is that ____    . A. young prairie dogs shouldn't move to other place B. young prairie dogs must find a new territory C. young prairie dogs should fight to gain more land D. young prairie dogs shouldn't get food from other territories 4.The following facts can make you believe prairie dogs do not  fight one another EXCEPT the one that___． A. they stay in their own sections of the town and eat only the plants that grow there B. the older animals move out of the town when they become too large for the food C. prairie dogs build the network of tunnels and burrows to form a territory in the town D. there was sunlight,fresh air and enough grass for all