Some Grammar I don't know .........

4. Present Perfect Continuous Tense﹝現在完成進行時態﹞

動詞的現在完成進行時態的形態是：have ( has ) been + 動詞的現在分詞

動詞的現在完成進行時態表示：過去已經開始而到現在還正在進行的動作或狀態

例如：
I have been reading this book for a week.
I have been waiting for him since three o'clock.


5. Past Perfect Continuous Tense﹝過去完成進行時態﹞

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.

通常都會有另一個past tense來表達另一個事件，以分別兩件事件的前後。

說不清楚的，歡迎再問。