过去完成时
过去完成时是一个相对时态，表示过去的过去，只有在两个过去发生的动作相比较时才可显示出来。
例：As soon as we got to the station, the train had left.
注：主从句表达的动作紧接时，即两动作发生的时间没有明显时间上的悬殊或空档时，主从句都可用一般过去时。
扩展资料
例： Where did your brother study before he joined the army?
过去完成时可表示截止过去某一时间动作的总或动作的结束。
例：By the end of last month. We had reviewed four books
By eight o`clock, he had finished his homework.
与这个时态连用的时间状语常有：
by 1985, by eight o`clock, by then, by the end of last month, by the time when, when, as soon as, before 等连词引导的时间状语从句，表示主句动作结束的时间。
现在进行时主要用于：
表示现在或现阶段正在进行的动作。
例： Listen, someone is crying.
What are you doing these days?
代替一般现在时，表示经常性动作或状态，而含有某种感情色彩。
例： How are you feeling today?
你今天感觉怎样?(显得亲切)
He is doing well in his lessons.
他的'功课很好。(赞扬)
You are always boasting.
你老爱吹牛。(厌烦)
动词 go, come, leave, arrive 等表将要发生的动作时。
例：They are leaving for Shanghai.
与这种时态连用的时间状语常有：
now, these days, recently, this week 等。
