题目

---- Let’s go to a movie after work, OK? ---- ______ A. Not at all.      B. Why not?      C. Never mind.    D. What of it? 答案：B已知实数a，b＞0，a，b的等差中项为，设，则m+n的最小值为（ ）A．3B．4C．5D．6