V-던데요 grammar = I saw/felt/surprised that ~express contradiction to one’s speaking or surprise to something

N/A/V-던데요 grammar = I saw/felt/surprised that ~express contradiction to one’s speaking or surprise to something

Usage:
- The expression -던데요 = -던- (recollection) + -(으)ㄴ데요 (background info, contrast or surprising situation) = express something contradictory to one’s speaking or express surprising feeling toward something.

- The expression -던데 can be used in mid-sentence to indicate the present situation is contrary to the past situation.

- The expression -았/었던데요 is used for things that ended in the past.

Tense:

Adjective / Verb + -던데요

좋다 -> 좋던데요.

쉽다 -> 쉽던데요.

크다 -> 크던데요.

아름답다 -> 아름답던데요. 

보이다 -> 보이던데요. 

먹다 -> 먹던데요.

건강하다 -> 건강하던데요.

Noun  + (이)던데요

의사 -> 의사던데요.

학생 -> 학생이던데요.

은행원 -> 은행원이던데요.

Examples:

1. 집이 작아서 더 물건을 둘 데가 없어서 고민해요.
- 지난번에 갔을 때는 집이 아주 커 보이던데요.

I am worried because my house is so small that there is no more room to put anything else.
- But it looked really big when I was there last time.

2. 오늘은 선생님 기분이 좀 좋아지셨어요?
- 아니요. 아까 보니까 오늘도 안 좋으시던데요.

Is the teacher feeling better today?
- No, I just was him a while, he was still not good today.

3. 이번 시험이 아주 쉬웠지요?
- 아니요. 저는 지난 시험보다 더 어렵던데요.

The exam this time was really easy right?
- No, I felt that it is harder than the last exam.

4. 어제 미나 씨하고 식사하셨어요?
- 네, 미나 씨가 한국 음식을 아주 잘 먹던데요.

Did you eat with Mina yesterday?
- Yes, I am surprised that Mina eats Korean food really well.

5. 안아 씨가 학생이지요?
- 아니요. 직원이던데요. 학교 근처 회사에서 일하더라고요.

Is Anna a student?
- No, she is an officer. She works in a company near the school.

6. 피아노를 배우기가 어렵지요?
- 아니요. 배위 보니까 생각보다 쉽던데요.

Is learning piano difficult?
- No. After learning, I felt it is easier than I think.

7. 어제 남산에 올라갔어요?
- 네, 남산에서 본 서울 야경이 아주 아름답던데요.

Did you climb Namsan yesterday?
- Yes, (I am surprised that) Seoul night view from Namsan is really beautiful.

8. 민수 씨가 잘 지내고 있지요?

- 네, 얼마 전에 회사를 옮겼던데요.

Is Minsu living well?

- Yes, I heard he recently changed jobs.

9. 앤디 씨는 좋은 사람 같아 보이던데 한번 만나 보세요.

Andy seemed like a good person, so you should meet him.

10. 어제는 많이 춥던데 오늘은 따뜻하네요.

It was really cold yesterday but it is warm today.

Differences between -더라고요 grammar and -던데요 grammar

Both the grammars can be used to recollect the past event. 

However, -던데요 grammar can be used to express an opinion contrary to one's saying while -더라고요 grammar can't. 

어제 본 영화는 재미있었조?

- 아니요. 저는 재미없던데요. 영화가 끝나기 전에 많은 사람들이 방을 떠났더라고요.

The yesterday movie is interesting, right?

- No, I felt it is boring. I saw many peoples left the room before the movie was over.