Question

[Linh Nguyễn]

The search (26) _______ alternative sources of energy has led in various directions. Many communi- ties are burning garbage (27) _______other biological waste products to produce electricity. Converting waste products to gases or oil (28) _______ also an efficient way to dispose of waste.

Experimental work is being done to derive synthetic fuels (29) _______ coal, oil, shale and coal tars. However that process (30) _______ proved to be expensive. Other experiments that are underway to harness power with giant windmills are also (31) _______ tested.

Some experts expect utility companies to receive hydroelectric power (32) _______ from streams and rivers. Fifty years (33) _______ hydroelectric power provided one third of the electricity used in the United States, but today it supplies only four percent. The oceans are another potential sources of energy. Scientists are studying ways to convert the energy of ocean currents, tides and waves (34) _______ electricity. Experiments are also underway to make use (35) _______ temperature differences in ocean water to produce energy.

Answer 1

[Trần Nguyễn Bảo Quyên]

The search (26) for alternative sources of energy has led in various directions. Many communi- ties are burning garbage (27) and other biological waste products to produce electricity. Converting waste products to gases or oil (28) is also an efficient way to dispose of waste.

Experimental work is being done to derive synthetic fuels (29) from coal, oil, shale and coal tars. However that process (30) has proved to be expensive. Other experiments that are underway to harness power with giant windmills are also (31) being tested.

Some experts expect utility companies to receive hydroelectric power (32) derived from streams and rivers. Fifty years (33) ago hydroelectric power provided one third of the electricity used in the United States, but today it supplies only four percent. The oceans are another potential sources of energy. Scientists are studying ways to convert the energy of ocean currents, tides and waves (34) to electricity. Experiments are also underway to make use (35) of temperature differences in ocean water to produce energy.