一、过去完成时的概念
过去完成时表示在过去某一时刻或某一动作之前发生的动作或状态, 句中常用by, before, until, when等词引导时间状语。过去完成时除了强调动作发生在过去之外, 还常用于间接引语和虚拟语气的句子中。例如:
*We had built five new buildings by the end of last year.
到去年年底, 我们已经建了五座新大楼。
*The classroom hadn’t been cleaned before the teacher came.
老师来之前教室还没有打扫过。
*The researchers said at least 4% of the population in those countries had been infected.
研究人员表示, 那些国家至少有4%的人口被感染。
*The letter was passed from one to another until everyone had read it. 这封信从一个人传到另一个人, 直到每个人都看完。
*Helen said(that)she had moved to another flat.
海伦说她已经搬到另一套公寓去了。
*If only we had listened to their advice!
要是我们听了他们的建议就好了!
