文档介绍
Animals in Danger Three billion years after life began, the earth is now the home to many different kinds of living things—perhaps five to ten million kinds. However，many of these are dying out. It is thought that between the years 1550 and 1950 an average(平均数) of one kind of living things died out each year. By 1985 this had risen to one per day. Between 1980 and 2012 we may lose another half a million different kinds of living things. There are many reasons for animals' dying out，but the most important one is the part that humans have played. First, many animals have been killed for food. Second, many of the places where these animals used to live have been destroyed. Dry lands have been watered. Wet lands have been turned into fields. Forests have been cleared. Much land has either