题干
—Mike invited us to take part in the party this Sunday.
—________ Is this Sunday his wedding anniversary(结婚纪念日)?
—________ Is this Sunday his wedding anniversary(结婚纪念日)?
A：Why not?
B：That’s all right.
C：What for?
D：What a good idea!
答案(点此获取答案解析）
C
，
，已知
∈B,且B中含有3个元素，则集合B有( )
