Half a century ago, most people lived in【B1】______areas. However, according

Half a century ago, most people lived in(26)rural areas. However, according to the most recent estimate projected by the United Nations,(27)more than half of all people will live in cities by 2012, for the first time in history. City life is not always a bad thing, but many experts worry about this process of(28)urbanization. According to a new report from the Worldwatch Institute, an environmental research group in Washington, it is having a huge(29)effect on human health and the(30)quality of the environment. Of the three billion people who live in cities now, about one billion live in(31)unplanned settlements. These are areas of poverty, slums, that generally lack basic services like clean water, or even(32)permanent housing. More than 60 million people are added to cities and their(33)surrounding areas each year, mostly in slums in developing countries. Molly O’Meara Sheehan,(34)the leading researcher of the Worldwatch report, believes that the international community has been too slow to recognize the growth of urban poverty. Policymakers, she says, need to increase investments in education, health care and other areas. The report talks about some successful efforts by local governments and community groups. For example, Freetown in Sierra Leone has established farming within the city limits to meet much of its growing food demands. In Bogota, the capital of Colombia, engineers have created a bus system that has helped reduce(35)air pollution and improve quality of life.