题目

Mr. Brown is 70 this year. Although he is very old, ____ he works very hard. A．andB．butC．soD．/ 答案：D解析:略已知全集U={1，2，3，4，5，8}，集合A={2，4}，B={2，4，8}，C={2}，D={4，8}，求：①A∩B；  ②B∪C；  ③（∁UA）∩C；  ④∁U（C∪D）