... water for power and fuel,rather than oil, coal, or nuclear power. A. Alternative B. Solar C. Hydropower D. Electricity26) Oil, coal and natural gas are ____ fuels made from decayed material. A. ... ____ nature. A. danger B. dangerous C. endanger D. endangered18) Many species of animals are threatened and could easily become ____. A. disappeared B. vanished C. empty D. extinct19) They started ... pollution. Moreover, plant waste and animal manure cost almost nothing.31) What is the role of energy to human beings? A. unimportant B. unnecessary C. necessary D. fundamental32) What do poor people...