设集合=                                               

A．{1，3}                                                      B．{1，2，3，4}

C．{1，3，5，7}                                           D．{1，2，3，4，5，7}

设集合A＝{1,2,3,4}，B＝{3,4,5}，全集U＝A∪B，则集合∁_U(A∩B)的元素个数为(　　)

A．1个              B．2个            C．3个           D．4个

设集合A＝{1,2,3,4,5,6}，B＝{4,5,6,7,8}，则满足S⊆A且S∩B≠∅的集合S的个数是                                                                                    (　　)

A．57                              B．56

C．49                              D．8

设集合A＝{1,2,3,4}，B＝{3,4,5}，全集U＝A∪B，则集合?_U(A∩B)的元素个数为(　　)

A．1个             B．2个              C．3个              D．4个

设集合A＝{1,2}，则A的子集个数是(　　)

A．1               B．3                 C．4            D．5