◇ The Past Perfect Continuous
過去完成進行式
過去完成進行式用來表達某動作在過去某個時間點開始持續進行，並已在過去某個時間點結束。例如例句 With all that in mind, it's clear how vital these elegant creatures are to the planet, and how much good they could've been doing if we hadn't been slashing their populations for decades. 其中的 if we hadn't been slashing their populations for decades. 意思是如果我們在過去幾十年沒有一直殲滅他們，「大量殲滅」的動作發生在過去，一直持續到過去的某個時間點結束。
Example：
1. The children had been playing and so the room was a mass.
孩子在們玩了一陣子之後，這個間變得很亂。
2. The pavement was wet, it had been raining.
人行道都是濕的，之前一定一直在下雨。
3. We'd been living in Budapest for three months when we had to leave.
在我們必須離開布達佩斯之前，就已經在那邊住了三個月。