았/었었다 [Intermediate Grammar]

- 았/었었다

→ It comes from overlapping a past tense stem-았/었' and another past tense stem -었.' It means 'it had done before based on a certain time of the past or the action or fact done in the past is different or isolated from the one in the present.'

Example: 

1.  지금은 키가 작지만 어렸을 때는 컸었어요.
    Even though I am small, I used to be tall when I was young.

2. 어제 선생님이 물어봤을 때 사실은 숙제를 하지 않았었어요.
    When my teacher asked me if I had done my homework or not yesterday, in fact, I hadn't
done it yet.

3. 저는 대학 시절에 사진 동아리 활동을 했었어요.
    I once joined a photo club when in college.

4. 이 건물이 옛날에는 병원이았었어요.

    This building was a hospital in the past.

5. 오전에 어떤 분이  찾아왔었어요.

    Someone came to see you this morning.