题目

---Is Mary still performing? ----I’m afraid not. She is said_____ the stage already. A. to have left      B. to leave   C. to have been left   D. to be left 答案：A 解析: 略要使二次根式有意义，那么x的取值范围是 A．x＞－1   B． x＜1    C． x≥1       D．x≤1