题目设集合A=(1,2,3),集合B=(2,3,4),则A-B为()。A. (1)B. (2,3)C. (1,2,3,4)D. (4)设集合A={1,2,3},集合B={2,3,4},则A-B为()。A. {1}B. {2,3}C. {1,2,3,4}D. {4}题目解答答案A. {1}