题目

________alone in the large house，the little boy had to learn to survive by himself. A．To leave  B．Leaving C．Left  D．Being left 答案：C 考查非谓语动词。句意：小男孩被单独留在一个大房子里，他不得不学着独立生存。leave和the little boy之间是逻辑上的动宾关系，故用过去分词。要使二次根式有意义，字母x必须满足的条件是（ ）A．x≥1B．x＞-1C．x≥-1D．x＞1