回复 45# 土地公
用华语解释可以吧,
就是两件未来的事情在同一个句子的时候。
当一件事情发生了,另一件就变成是之前那件事的past tense。
For example:
The train will leave the station at 9am. You will arrive at the station at 9.15am. When you arrive, the train
will have left.
Past perfect continuous/Past perfect progressive.
在句子里是[had been + present participle]
就是一件事情【有持续性的,所以用-ing】发生在过去的。比如说,
Examples:
You had been waiting there for more than two hours when she finally arrived.
Had you been waiting there for more than two hours when she finally arrived?
You had not been waiting there for more than two hours when she finally arrived.