Early people had very little effect on the environment. They lived in caves in very small “clan” groups. They collected or killed only enough for the clan’s survival. Early clans were nomadic, which mean that they didn’t stay in one place. Instead, they moved around, following the animals that were their main food source and seeking areas where seasonal plants grew wild. Moving around seasonally helped to protect the environment. The land had time to recover and animals had time to breed (繁殖)before the clan returned for the next season.. As time went by, these small family clans joined with others to form larger groups for protection. Joining with other clans gave them more hunters and more women to help cut up the meat and share it between families. Eventually, people tamed(驯养)wild animals such as dogs and horses. People settled around rivers and fertile plains to share responsibilities and duties. Then, people began to plant crops instead of moving to areas where the plants grew. This development changed the environment. Traditional forms of work also changed. Some people were better at performing a particular task than other clan members, so then began to specialize in things they were good at doing. This also meant that they began to exchange their goods for things that others produced. People began to communicate with distant tribes. Land was cleared for roads. Foreign plants and animals were transported to places where they had not existed before. Specialization also give people more free time. So art ,dance and music became important ways of expressing feelings and thoughts. This was how many great civilizations started. Compared to the past, modern civilization has experienced many changes to become the highly developed society that exists today. Populations have increased rapidly. Forests have been cleared for farms. Inventions and technology have made work easier. However, pollution and other serious problems have also resulted from human progress. As concerned citizens, it is up to us to learn from past mistakes and to help maintain and improve our environment. 小题1:Early tribes didn’t have much effect on animal population because_____ A .they kept animals for themselves         B they ate only vegetables C they loved animals                     D they killed only enough for food 小题2:The main purpose for small clans to join together was_____ A to hurt animals                         B to seek safety C to share caves                         D to protect environment 小题3:According to the passage ,we can learn that_____ A early people moved to new places looking for new sources of food B modern civilization began when people started to live together in big groups C modern advancements are always good for the environment D people began to exchange goods because they didn’t have enough money 小题4:It can be concluded from the passage that_____ A human progress has brought civilization to the society B civilization has improved traditional forms of work C early people understood environmental protection D our environment has been affected by human progress