B
Prairie dogs（草原犬鼠）are native to the prairies of the United States, Canada, and Mexico. They are actually a type of squirrel named for the place where they live and the warning call they give when they are threatened（威胁）, which sounds similar to a dog’s bark. One of the amazing things about prairie dogs is the way that they live in “towns.” These towns can contain many hundreds of prairie dog families.
Prairie dogs like to live with other prairie dogs, so they join together to make prairie dog towns. These are collections of prairie dog families that can cover one or two square kilometers. Prairie dog towns are big because each family lives in their own tunnel（地道）system, which is usually 10-30 meters wide. Families are usually made up of 1 male, 2 to 4 females, and their children. When the young prairie dogs reach three years of age, they leave home to found their own families on the edges（边缘）of the town.
Prairie dog tunnels usually have several chambers. These chambers are like rooms in a house. Female prairie dogs use them when they give birth and when they raise their babies. The other chambers are used by the family for sleeping. To make them comfortable, prairie dogs separate the chambers by lining the walls with grass. The tunnels are also used for protection when prairie dogs are threatened by other animals. For this reason they are designed with two or more holes serving as doors.
Prairie dogs like living in towns and they even make social visits to each other. When two friendly prairie dogs meet, they greet each other with a kind of kiss. However, the male prairie dogs defend the borders of the family’s tunnel system against enemies. Prairie dog towns have conflicts, social gatherings, and cooperation just like a human town, which makes them very interesting.
24. What do we know about prairie dogs?
A. They bark like squirrels. B. They are group animals.
C. They are an endangered species. D. They are wild dogs living on grasslands.
25. How does the author explain the function of chambers in Paragraph 3?
A. By giving the meaning of chambers. B. By describing how chambers are built.
C. By comparing chambers to human homes. D. By classifying the contents of chambers.
26. Why are tunnels designed with many holes?
A. To let in fresh air. B. To make it comfortable for sleep.
C. To avoid being crowded in and out. D. To run away from dangerous enemies.
27. The last paragraph is mainly about prairie dogs’ ________.
A. social life B. social structure C. hunting habits D. living environment
