[单选题] 由5个1、2个2排成含7项的数列，则构成不同的数列的个数是-湖北继续教育网网校

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[单选题][单选题] 由5个1、2个2排成含7项的数列，则构成不同的数列的个数是

A21

B25

C32

D42

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