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Since the great oil crisis of the 1970s, the International Energy Agency has encouraged and supported research carried out to discover alternative energy sources. |
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Since there was a great oil crisis in the 1970s, the International Energy Agency has been encouraging and supporting research into alternative energy sources. |
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Following the serious oil crisis of the 1970s, the International Energy Agency has been encouraging and subsidising any research pertaining to alternative energy resources. |
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Following the great oil crisis of the 1970s, the International Energy Agency has encouraged research that might lead to the discovery of alternative energy sources. |
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The great oil crisis of the 1970s convinced the International Energy Agency of the need to support research into the development of alternative energy resources. |