A. SHOWS B. PRODUCES C. RESULTS D. APPEARSQUESTION 46-50

45. a. shows b. produces c. results d. appearsQUESTION 46-50: Read the following passage carefully and answer the questions that follow by circling letter A, B, C or D as the correct answer and then mark your choice on the answer sheet.The research for alternative sources of energy has led in various directions. Many communities are burning garbage and other biological waste products to prodecu electricity.converting waste products to gases or oil is also an efficient way to dispose of waste.Experimental work is being done to derive synthetic fuels from coal, oil shale and coal tars. But to date, that process has proved expensive. Other experiments are underway to harness power with giant widmills. Geothermal power, heat from the earth, is also being tested.Some experts expect utility companies to revive hydroelectric power derived from streams and rivers. Fifty years ago, hydroelectric power provided one third of the electricity used in the United States, but today it supplies only four percent. The ocans are another potential sourse of energy. Scientists are studying ways to convert the energy of ocean currents, tides and waves to electricity. Experiments are also underway to make use of temperature differences in ocean water to produce energy.