過去完成進行時的延續性動詞
在英語過去完成進行時中，例如 work、study、stay、sing、teach等延續性動詞與表示一段時間的時間狀語連用時，用過去完成進行時可以表示一個動作一直延續到過去某一時刻，通常強調動作的持續性和不間斷性。例如：
1.She had been studying for two hours when her classmate came to visit her.
當她的同學來看她的時候，她學習有兩個小時了。
2.I had been writing a letter for two hours by the time she came to see me.
當她來看我的時候，我已經寫了兩個小時的信了。
3.They had been having breakfast for ten minutes when Tom came in.
湯姆來時，他們已經吃了十分鐘的早飯了。
4.She had been dancing for one hours when her mother came back home.
當她的媽媽回到家時，她跳舞有一個小時了。
5.I had been reading this book for three hours by the time she came to see me.
當她來看我的時候，我已經讀了三個小時的書了。
6.They had been having class for twenty minutes when Tom came in.
湯姆來時，他們已經上了二十分鐘的課了。
7.My father had been watching TV for two hours when his friend came to visit him.
當他的朋友來看他的時候，我的父親已經看了兩個小時電視了。
8.Tom had been playing piano for two hours by the time Lily came to see him.
當麗麗來看他的時候，湯姆已經練習鋼琴兩個小時了。
9.We had been talking about this project for one hour when manager came in.
經理來時，關於這個項目，我們已經討論了一個小時了。
