题目内容
已知集合A={1,2,3,4,5},B={(x,y)|x∈A,y∈A,x-y∈A};则B中所含元素的个数为( )
A.3 B.6
C.8 D.10
已知集合A={1,2,3,4},B=,则A∩B=( )
A.{1,2,3,4} B.{1,2} C{1,3} D.{2,4}
已知集合A={1,2},B={2,4},则A∪B=
A.{2} B.{1,2,2,4} C.{1,2,4} D.