题目

______ we want to get to Chicago by sunset, it means having to leave at dawn tomorrow. A . If B . After C . While D . Where 答案：A函数f（x）=[x]的函数值表示不超过x的最大整数，例如，[-3.5]=-4，[2.1]=2，当x∈（3，4.5]时，f（x）=[x]的解集为（ ）A．{3，4}B．{4}C．{3}D．（3，4.5]