题目

Be quiet! I have ______ to tell you. A. nothing important    B. important nothing    C. something important   D. important something 答案：C已知全集是U，集合M和N满足M⊆N，则下列结论中不成立的是（ ）A．M∩N=MB．M∪N=NC．（∁UM）∩N=∅D．M∩（∁UN）=∅