✔ 最佳答案
past perfect continuous tense
動詞的過去完成進行時態的形態是:
had been + 動詞的現在分詞
動詞的過去完成進行時態表示:
過去某一時間以前已經開始而到那時還正在進行的動作或狀態
例如:
They had been playing ball for an hour when you reached
the playground.
I had been doing my homework for three hours when he
visited me yesterday.