Great Wall of China
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Toilets
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2.9 |
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Machu Picchu
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X-Rays
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2.8 |
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Parthenon
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Light Bulbs
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2.8 |
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Solar Panels
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2.9 |
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Taj Mahal
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TVs and Remote Controls
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2.9 |
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Colosseum
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Refrigerators
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2.9 |
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Petra
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Big Ben
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Germ Theory
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2.9 |
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Vaccines
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2.9 |
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Smart Homes
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2.9 |
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Antibiotics
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2.9 |
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Indonesia
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Turning Points in U.S. History (10 titles)
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Costa Rica
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Iceland
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Denmark
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Cambodia
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Chile
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