In a way, all of us are on a spaceship-the planet Earth. We move around the sun at 18 miles per second and never stop. On our spaceship, we have 5 billion people and limited supply of air, water and land. These supplies have to be used carefully because we can't buy new air, water or land from anywhere else. Environment on our planet is a closed system. Nothing new is ever added. Nature recycles its resources. Water, for example, evaporates and rises at visible drops to form clouds. The same water returns to the earth as rain or snow. The rain that falls today is actually the same water that fell on the land 70 million years ago. Today, the earth is in trouble. Factories pour dirty water into rivers, many fish die and water becomes unhealthy for people to drink. Cars and factories put poisons into the air and cause plants, animals and people to get sick. People throw bottles and paper out of their car windows and roadside becomes covered with all sorts of wastes. Over the years people have changed environment and we have pollution. To continue to survive, we must learn how to use the earth resources wisely. We have to change our habits and stop dropping such enormous amounts of industrial waste into the water and air. We must cooperate with nature and learn better ways to use, not to abuse our environment.
Questions 32 to 35 are based on the passage you have just heard.
32. Why does the speaker compare the earth to a spaceship?
解析：短文开篇便将地球比作了spaceship，然后说上面的空气、水、土地资源都很有限，因此答案为A。根据选项可以预测信息点是地球与宇宙飞船之间的相似处。答案中的关键词limited supply of air, water为文中原词。
33. How fast does the planet Earth travel around the sun?
34. Why does the speaker advise us to use the earth resources wisely?
35. What message is the speaker trying to convey?