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 ![]() Workers build a steel tower for electric power in the mountains at an altitude of about 4,700 meters in Tibet autonomous region on April 23, 2011. [Photo/Xinhua] 
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 ![]() Workers build a steel tower for electric power in the mountains at an altitude of about 4,700 meters in Tibet autonomous region on April 23, 2011. [Photo/Xinhua] 
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