题目

Only after I had known him for some time      to appreciate his real worth. A．do I begin                               B．did I begin C．I began                                      D．had I begun 答案：B 设函数(a＞0，且a≠1)，若用[m]表示不超过实数m的最大整数，则函数[]＋[]的值域为________．