Question

{a,b}包含于A包含于{a,b,c,d,e,f},集合A为

Answer 1

集合A

{abc}

{abd}

{abe}

{abf}

{abcd}

{abce}

{abcf}

{abcde}

{abcdef}

{abdef}

{abdf}

{abef}

.就是集合A一定有元素{a b}

可能有{cdef}一个或2个或3个或4个元素