Read the passage carefully and choose the best answer to each question.
The research of alternative resources of energy has resulted in various directions. Many communities are burning garbage and other biological waste products to produce electricity. Changing waste products into gases or oil is also an efficient way to dispose of waste. Experimental work is being done to make synthetic fuels from coal, or coal tars. But today, that process has proved expensive. Giant windmills have been built to provide a considerable source of electricity. Other experiments in geothermal power are being tested to harness power deep inside the earth.
Some experts are trying to revive hydroelectric power which is 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 oceans are another source of energy. Scientists are studying ways to change the energy of ocean currents, tides, and waves into electricity. Experiments are also underway to make use of temperature differences in ocean water to produce energy.
What percentage of the electricity used in the United States did hydroelectric power use to provide?
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Lời giải:
Báo saiGiải thích: Fifty years ago, hydroelectric power provided one-third of the electricity used in the United States, but today it supplies only four percent. => Năm mươi năm trước, thủy điện cung cấp một phần ba lượng điện được sử dụng ở Hoa Kỳ, nhưng ngày nay nó chỉ cung cấp bốn phần trăm.
Tạm dịch: Bao nhiêu phần trăm điện năng được sử dụng ở Hoa Kỳ mà thủy điện đã sử dụng để cung cấp?
A. trên 30%
B. dưới 50%
C. 4%
D. 40%.