结构推理 Directions: In this part there is a short passage with five questions or incomplete statements. Read the passage carefully. Then answer the questions or complete the statements in the fewest possible words (not exceeding 10 words). As people turned from hunter gatherers to farmers in the Neolithic (新石器时代) period, population began to increase significantly. This was partly due to increased food supplies, as farming techniques allowed production of more food on any given piece of land, and partly because of a decline in death rates as people took up a more settled existence. But it apparently also occurred because birthrates increased substantially for the first time in human history. Because of their wandering lifestyles, hunter/gatherer societies tend to have fewer children. A mother in such a society can carry only one child and what few possessions the family might have as her community moves about. Other children must be old enough to keep up with the tribe as it moves, so they do not become a burden on the community. This reality dictates that children must be spaced about four years apart―something hunter/gatherer societies achieved through sexual abstinence (禁欲), extended nursing, abortion (堕胎), or infanticide (杀害婴儿). Farming societies, by contrast, stay in one place with their crops. Because mobility of children is not a consideration, and because children can contribute to food production from an early age, birthrates in farming communities are higher, often with birth spacing averaging only two years. All these factors contributed to higher population densities as human lifestyles shifted from hunting-gathering to farming. 1.When hunting-gathering societies had turned into farming ones, population increased significantly because of 2.What is the most probable result of the lifestyle in hunting-gathering societies? 3.How to decrease birthrates in the Neolithic period? 4.Why farming societies are likely to have more children? 5.What conclusion can you draw from the passage?