The first zoo was established around 3,500 years ago by an Egyptian queen for her 24enjoyment. Five hundred years later, a Chinese emperor built a huge zoo to show his power and wealth. Later zoos set up the purpose of 25animals. Some of the early European zoos consisted of dark holes or dirty cages, which 26people feel disgusted(厌恶的). Later the zoos 27by research centers and modern zoos where animals were studied and kept in good condition. These places became the first modern zoos. As early as the 1940s, scientists understood that many kinds of wild animals were faced 28extinction. Since then, zoos have been trying to save many endangered species, but relying on zoos 29species is not enough. The best method of protection is to leave them in their natural habitat. Today animals in large and natural reserves are fed with a balanced diet and are watched 30for any sign of disease. With specially trained keepers looking after them and some hospitals 31they can receive treatment when ill., all the animals there live 32comfortable life. Anyway, it is true that zoo breeding 33have played an important role in the attempt to save many species of wildlife.