【正文】 lives alone. Most animals must live in a group, and even a plant grows close together with others of the same kind. Sometimes one living thing kills another. One eats and the other is eaten. Each kind of life eats another kind of life in order to live, and together they form a food chain(鏈 ). Some food chains are simple, while others are not. But all food chains begin with the sun, and all food chains bee broken up if one of the links disappears. All life needs sunlight to live on. But only plants can use sunlight directly. Plants are “factories”. They make food from sunlight, water and things in the soil and air. Plants feed all other living things. Animals can only use the sun’s energy after it has been changed into food by plants. Some animals feed directly on plants. Others eat smaller animals. Meateating animals are only eating plants indirectly. What about human beings? We are members of many food chains. We eat wheat, rice, vegetables, fruit and so on. We also eat meat and drink milk. But men often break up the food chains. They kill wild animals. They also make rivers, lakes and seas dirty. When these rivers, lakes and seas are polluted, the fish in them can not be eaten. If men eat the fish, they will get strange diseases. Each form of life is linked to all others. Breaking the links puts all life in danger. 33. How does every living thing on the earth live? A. Each plant can live alone. B. Each animal can live alone. C. If living things want to live, they must kill each other. D. Every living thing on the earth cannot live without others. 34. Plants make food from ________. A. sunlight, water and things in the soil and air B. water, sunlight and things in the air C. water and things in the soil and air D. water, sunlight and things in the soil 35. Who often break up the food chains? A. Human beings B. Animals. C. Plants and animals. D. Men and wild animals. 36. Which of the following do you think is the best title for this passage? A. Animals. B. Plants. C. Food Chains. D. Living Things. D Pollution means adding dirty or harmful things to land, air, water and so on. As a result, they are no longer pleasant or safe to use. Pollution is bad for animals and plants, and it even makes people’s health in danger. In our daily life, we can see different kinds of pollution in many places. There are three main forms of pollution: land pollution, air pollution and water pollution. Land pollution is caused by solid waste, such as cans, bottles and some plastic things which aren’t broken down quickly. It makes the environment look very bad. However, air pollution is more serious than land pollution. It is much worse in cities and towns because of the fumes(廢氣 ) from traffic and the waste from human activities. When people drive their cars, fumes which are most made up of CO2, NO2 and SO2 are given off. After the gases get into the air, they may mix with clouds. Then they will bee some harmful chemicals falling on the ground with rain. It is one of the reasons for soil erosion(土壤侵蝕 ) which is one example of water pollution. Various kinds of pollution will cause many health problems. People have realized they must change this serious situation. There are many ways to control pollution. To develop alternative energy(替代能源 ) is very popular in many countries. China, for example, has made up its mind to be a leader in this field. It is trying hard to make full use of energy from the sun and w