Read the passage carefully and choose the best option to fit each space.

People are rapidly destroying the world's tropical forests. In 1950, tropical forests (23)......about 8,700.000 square miles of the earth or about three-fourths of Africa. Today less than half the original extent of the earth's tropical forests remains. Few tropical forest species can adjust to disturbance of their habitat. Most die when people clear large areas of forests. Scientists estimate (24)......tropical deforestation wipes out about 7,500 species per year. Commercial logging and the expansion of agriculture have (25)......or wiped out wide areas of tropical forests. Huge mining projects, the construction of hydro-electric dams have also narrowed forest areas

A complex combination of social, political and economic factors has caused these destructive activities. Rapid population growth and poverty often intensify the pressure to clear tropical forests for short-term economic benefits. Brazil, Indonesia, and other nations have (26)......tropical forests to create new settlements that allow people to move out of overcrowded cities. Many conservation organizations are working with governments to conserve tropical forests. Such efforts include establishing protected areas, (27)......intelligent management of tropical forests and increasing awareness about the importance of tropical forests.