题目内容：

Zoos have been around for centuries — and they’ve changed a lot over the years. In the Middle Ages, wealthy people kept animals in their gardens. Public animal parks appeared in European cities in the late 1700s and early 1800s. The Philadelphia Zoo, the first in the United States, opened in 1874.

         Until a few decades (十年) ago, most zoos were organized by creatures — monkeys in one area, cats in another, birds somewhere else, just like museum collections. In recent years, zoos have instead begun grouping animals that would normally interact (互相作用) in the wild. Moreover, instead of closing animals behind bars, designers are creating landscapes like the environments in which these creatures would naturally be found. Nearby signs provide information about the animals and their habitats in parts of the world where they normally live.

         The Denver Zoo’s new Predator Ridge exhibit, for example, aims to teach visitors about Africa. Eight acres of land provide homes for 14 animal species, including lions, porcupines, cranes, and wild dogs. Plants from the region grow alongside African-like landform. Ten-foot-tall mounds (土墩) give lions a place from which to survey their surroundings, just as they would do in the wild.

         Landscape design makes visitors to the Denver Zoo’s Predator Ridge exhibit feel like they’re really in Africa.

         Animals in Predator Ridge can’t actually be mixed with one another, for safety reasons. But hidden deep channels and other smart features allow visitors to see all the animals at once. Different species can see each other too.

1.What is the passage mainly about?

A. Protection of zoo animals.

B. Changes of zoos over the time.

C. The safety problem of zoos.

D. The living habits of zoo animals.

2.In the Denver Zoo ten-foot-tall mounds are built to _____.

A. protect the safety of visitors

B. separate lions from other animals

C. create a natural environment for lions

D. offer visitors a better view of lions

3.The underlined part “the region” in Paragraph 3 probably refers to _____.

A. Africa                         B. the Predator Ridge exhibit  

C. the Denver Zoo                D. the ten-foot-tall mounds

4.We can learn from the passage that _____.

A. the earliest zoos were probably rich people’s gardens

B. the Philadelphia Zoo is the first zoo in the world

C. the new Predator Ridge exhibit is held in Africa

D. more animals will be kept in zoos in the future