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3,17,21,25,(),33。 A. 27 B. 29 C. 31 D.
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31 29 23 () 17 13 11 A.21 B. 20 C. 19 D. 18
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4,6,5,7,7,9,11,13,19,21,() A. 27,29 B. 32,33 C. 35,37 D.41,43
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11,13,17,19,23,() A.27 B.29 C.31 D.33
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13, 17, 21, 25, (), 33。A.27 B.29 C.31 D.32
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3,5,9,13,21,25,()A.27B.29C.31 D.33
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13,17,21, 25,(),33。A.27 B.29 C.31 D.32