过去完成时用于描述在过去某一时间点之前已经完成的动作或状态。以下是过去完成时的一些常见标志词:
介词短语:
by + 过去时间(例如:by the end of last year, by the time of last night)
before + 过去时间(例如:before she left the city)
after + 过去时间(例如:after the game started)
since + 时间段(例如:since the beginning of the year)
连词:
when + 过去时间(例如:when I arrived, when the bus left)
before + 过去时间(例如:before the meeting started)
after + 过去时间(例如:after the game ended)
until + 过去时间(例如:until the last minute)
副词:
already(已经)
just(刚刚)
ever(曾经)
never(从未)
yet(还)
其他表达:
up to/till + 过去时间(例如:up until last night, up till then)
by the time + 从句(例如:by the time the movie started, I had already eaten dinner)
使用过去完成时,可以强调某个动作或状态在另一个过去的动作之前已经完成。例如:
By the time the movie started, I had already eaten dinner. (电影开始的时候,我已经吃过晚饭了。)
Before she left the city, she had used up all her savings. (在她离开这个城市之前,她已经用光了所有的积蓄。)
希望这些信息能帮助你理解过去完成时的标志词和使用方法