A、They live in twenty rainforests. B、They live in several hundred different varieties of trees. C、They live in a forty-degree ba

Rainforests circle the globe for twenty degrees of latitude on both sides of the equator. In that relatively narrow band of the planet, more than half of all the species of plants and animals in the world make their home. Several hundred different varieties of trees may grow in a single acre, and just one of those trees may be the habitat for more than ten thousand kinds of spiders, ants, and other insects. More species of amphibians, birds, insects, mammals, and reptiles live in rainforests than anywhere else on Earth.
   Unfortunately, half of the world’s rainforests have already been destroyed, and at the current rate, another 25 percent will be lost by the year 2010. Scientists estimate that as many as fifty million acres are destroyed annually. In other words, every sixty seconds one hundred acres of rainforest is being cleared. By the time you finish listening to this passage, two hundred acres will have been destroyed! When this happens, constant rains erode the former forest floor, the thin layer of soil no longer supports plant life, and the ecology of the region is altered forever. Thousands of species of plants and animals are condemned to extinction and, since we aren’t able to predict the consequences of this loss to a delicate global ecology, we don’t know what we may be doing to the future of the human species as well.
Questions 19 to 21 are based on the passage you have just heard.
19. Where do more than half of all the species of plants and animals live?
20. What is the current rate of destruction?
21. What will not happen if the rainforest continues to be cleared?