题目

The _________ shoes were covered with mud, so I asked them to take them off before they got into _________ car. A. girl’s; Tom’s        B. girls’; Toms’        C. girls’; Tom’s        D. girl’s; Toms’ 答案：Cf（x）=x2  x＞0π    x≤0，则f{f[f（-3）]}等于（　　）A．0B．π 4C．π2D．9