深圳报一个商务英语口语培训班多少钱
一、“已完成”：表示一个动作或状态在过去某时之前已经完成或结束。
I had finished my homework when my friends came.
我朋友来的时候，我就已经完成家庭作业了。
My father had left for Beijing before I came home.
在我到家前，爸爸已经离开去北京了。
二、“未完成”：表示一个动作或状态在过去某时之前已经开始，一直延续到这一过去时间，而且到那时还未结束，仍有继续下去的可能性。
Jack said that he had made much progress in English since he came here.
杰克说自从他到这儿以后，英语已经取得了很大进步。
By six o’clock these workers had worked twelve hours.
到六点钟时，这些工人已经工作十二小时了。
三、连词引导过去完成体用法：有些连词引导的过去完成时可互换。
When I reached the station, the train had already left.
=I reached the station after the train had left.
=I didn’t reach the station until the train had left.
=The train had left before I reached the station.
在我到车站时，火车已经走了。
美联英语培训学校
