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Complete the passage with a suitable word in each blank]
about twenty percent of the word's present energy already comes from the sun in one form or another. special devices have already been made avaiable to (1)........... on the roofs of houses and flats to (2) ......... the sun's rays and thus heat water. Thousands (3)............ these devices are now being used to provide (4)............ in homes throughout the United States while more (5).............. a millon solar water-heating units have already been (6)................ in homes in Japan. Other purposes for which (7)......... energy is at preaent being used include the (8)........... of salt from seawater, irrigation and sewage disposal. (9).......... most people in deleloping countries, the need is (10)........... for air-conditioners or central heating but for cheap (11)............ of cooking food, drying crops lighting homes
about twenty percent of the word's present energy already comes from the sun in one form or another. special devices have already been made avaiable to (1)........... on the roofs of houses and flats to (2) ......... the sun's rays and thus heat water. Thousands (3)............ these devices are now being used to provide (4)............ in homes throughout the United States while more (5).............. a millon solar water-heating units have already been (6)................ in homes in Japan. Other purposes for which (7)......... energy is at preaent being used include the (8)........... of salt from seawater, irrigation and sewage disposal. (9).......... most people in deleloping countries, the need is (10)........... for air-conditioners or central heating but for cheap (11)............ of cooking food, drying crops lighting homes