Before the 1960's, thirteen percent of adult Americans were college graduates, but the expansion of the educational system increased such an amount up to thirty-three percent by 1980.
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Aincreased such an amount up to
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Bincreased this figure to
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Cincreased such a number to
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Dhas upped such a number to
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Eincreases the total to
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显示答案
正确答案: B