Most new people were born in developing countries. These countries are found in much of Africa, South America and some parts of Asia. In the developed countries of Europe and North America, the population is growing very slowly. This is because women in these countries have, on average (平均), only one or two children. In the developing countries, many women have five or more children. In 1950, around one quarter of the world's population lived in the developed countries. By 2050, these countries will be home to only around one tenth of the world's people.

　　In the developing countries, more than one billion people are still living below the poverty (贫困) line. These people do not have enough food to eat and they live in poor housing. Children get little time at school and people suffer from many kinds of diseases.

　　At the beginning of the 21st century, the world's population was around six billion people. The U．N. has said that the world's population will level off (平稳下降) at 12.5 billion by the year 2100. Other groups think the world's population will continue to grow, reaching 14 billion before it becomes stable (稳定的), or even falls.

　　Section_ⅠIntroduction & Reading - Pre­reading

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