第13题: [单项选择]It is human nature to think back to a Golden Age ______one's country was strong and respected. A. when B. provided C. as D. unless 参考答案:A 答案解析:[考点] 定语从句 句中应该用关系副词when作连接,表示时间的定语从句,修饰Golden Age。千万不能把它看成时间状语从句,那样就无法合理理解句意了.四级考试中经常考查用关系副词when或者