过去完成时,也称为"过去未曾完成时",是英语中的一个时态,它表示一个在过去某个时间点或动作之前已经完成的动作或状态。它通常与"by"、"before"、"had"等词连用,用来描述一个在过去已结束的动作对过去的某个时间产生影响。
以下是几个过去完成时的例子:
1. 例句1:
"By the time I arrived home, my dinner had already been cooked." (当我到家时,晚餐已经做好了。)
2. 例句2:
"She had finished her homework before her mother came back." (她在妈妈回来之前就已经完成了作业。)
3. 例句3:
"They had lived in that house for 20 years before they moved." (他们搬家前,在那所房子里住了20年。)
4. 例句4:
"He had studied all night, so he passed the exam." (他整晚都在学习,所以考试通过了。)
在这些例子中,"had"是过去完成时的标志,表明动作发生在过去的过去。
过去完成时常常通过以下几个标志词和表达来表示:
1. "had":这是过去完成时的主要标志,通常位于句首或动词前,如 "I had studied" 或 "They had already left".
2. "had" 的各种变化形式:
"had+过去分词",如 "had finished" 或 "had eaten".
"had been" 的结构,用于强调持续性,如 "had been living" 或 "had been working"。
3. 表示过去的过去时间状语:
"by" 或 "before",如 "by the time I arrived" 或 "before she died".
使用 "just" 或 "already" 等副词,如 "He had already arrived" 或 "She had just finished".
4. 使用虚拟语气时,过去完成时用于描述与现在事实相反的情况,标志词可能是 "if" 后面接 "had",如 "If I had known, I would have come earlier."
5. 其他类似短语:
"The first time I had seen her",表示过去某个时刻之前已经见过。
"They had never been to that city",表示之前从未去过。
记住这些标志词可以帮助你更好地识别和运用过去完成时。