满足条件{1,2,3}⊆M⊊{1,2,3,4,5,6}的集合M的个数是(  ) A.7 B.8 C.9 D.10

问题描述:

满足条件{1,2,3}⊆M⊊{1,2,3,4,5,6}的集合M的个数是(  )
A. 7
B. 8
C. 9
D. 10

因为{1,2,3}⊆M⊊{1,2,3,4,5,6},所以集合M中至少含有元素1,2,3.且M≠{1,2,3,4,5,6},
所以M={1,2,3},{1,2,3,4},{1,2,3,5},},{1,2,3,6},{1,2,3,4,5},{1,2,3,4,6},{1,2,3,5,6}.
共7个.
故选A.