根据短文填空
It is good to keep animals in zoos. Zoos are places for people to see many different kinds of animals from all over the world. Without zoos, most people would never see a real tiger or bear. Secondly, zoos look after the animals very well. The animals are always given food and cleaned on time. In the wild, it is not always possible for an animal to find food, so sometimes it goes hungry. Thirdly, Zoos protect the animals. They offer them safe place to live in. In the wild, some kinds of animals are in danger of becoming extinct (灭绝). But zoos give these animals a chance to live. Without zoos, there would be fewer kinds of animals in the world.
However, some people think it is unnatural (非自然的) and unfair to keep wild animals in cages. Most animals are kept in cages that are too small for them. The animals such as bears and tigers always look sad in cages. Wild animals should look for their own food.
