Over half the world's people now live in cities. The latest "Global Report on Human Settle

ments" says a significant change took place last year. The report【C1】______this week from U. N. Habitat, a United Nations agency.

A century ago,【C2】______than five percent of all people lived in cities.【C3】______the middle of this century it could be seventy percent, or【C4】______six and a half billion people. Already three-fourths of people in【C5】______countries live in cities. Now most urban population【C6】______is in the developing world.

Urbanization can【C7】______to social and economic progress, but also put【C8】______on cities to provide housing and【C9】______. The new report says almost two hundred thousand people move【C10】______cities and towns each day. It says worsening inequalities,【C11】______by social divisions and differences in【C12】______, could result in violence and crime【C13】______cities

plan better.

Another issue is urban sprawl(无序扩展的城区). This is where cities【C14】______quickly into rural areas, sometimes【C15】______a much faster rate than urban population growth.

Sprawl is【C16】______in the United States. Americans move a lot. In a recent study, Art Hall at the University of Kansas found that people are moving away from the【C17】______cities to smaller ones. He sees a【C18】______toward "de-urbanization" across the nation.

【C19】______urban economies still provide many【C20】______that rural areas do not.

【C1】

A．came on

B．came off

C．came over

D．came out