Using technology as new as space-age fabrics and as ordinary as common dry-cleaning chemicals, scientists and historians, in their attempt at cleaning and preserving the American flag that flew over Fort McHenry in Baltimore in 1814, are hoping that it will then last another 200 years.
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Aand as ordinary as common dry-cleaning chemicals, scientists and historians, in their attempt at cleaning and preserving the American flag that flew over Fort McHenry in Baltimore in 1814, are hoping
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Band as ordinary as common dry-cleaning chemicals, scientists and historians are attempting to clean and preserve the American flag that flew over Fort McHenry in Baltimore in 1814, hoping
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Cand as ordinary as common dry-cleaning chemicals, an attempt by scientists and historians to clean and preserve the American flag that flew over Fort McHenry in Baltimore in 1814 is being made in the hope
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Dbut also as ordinary as common dry-cleaning chemicals, scientists and historians who are attempting to clean and preserve the American flag that flew over Fort McHenry in Baltimore in 1814, hoping
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Ebut also as ordinary as common dry-cleaning chemicals, an attempt by scientists and historians at cleaning and preserving the American flag that flew over Fort McHenry in Baltimore in 1814 in hopes
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正确答案: B