가: 아까 낮에 뭐 했니?
What did you do this afternoon?
나: 만화책을 읽다가 친구하고 같이 외출했어요.
I was reading a comic book, but then I went out with a friend.
가: 은혜야, 오랜만이다. 웬일이니?
Hey, Eunhye, it’s been a while. What’s up?
나: 이메일을 쓰다가 생각이 나서 그냥 전화했어.
I was writing an email and then thought (about you), so I just called.
This expression is used to indicate the speaker’s interruption of one action to immediately start doing the mother’s action. -다가 can be shortened to the form -다.
• 밥을 먹다가 전화를 받았습니다.
I was eating and then answered the phone,
• 공부를 하다가 졸았습니다.
I was studying and then dozed off.
• 지하철 1 호선을 타고 가다가 시청역에서 2호선으로 갈아타세요.
Take subway line 1, and then change to line 2 at City Hall Station.
• 스케이트를 타다가 넘어져서 다쳤어요.
I was skating and then fell and hurt myself.
1. This expression is also used to indicate that the action in the preceding clause continues while the action in the following clause occurs.
• 잠을 다가 무서운 꿈을 꿨어요.
I was sleeping and had a scary dream.
• 길을 걸어가다가 갑자기 생각이 나서 전화했어.
I was walking along and suddenly thought (of you), so I called.
• 친구하고 이야기를 하다가 웃었어요.
I was talking to my friend and laughed. (= laughed while talking to my friend)
2. The subject of the preceding and following clauses must be the same.
• (내가) 밥을 먹다가 전화가 왔습니다. (X )
->(내가) 밥을 먹다가 (내가) 전화를 받았습니다. (〇)
The sentence is ungrammatical because the subject of 전화가 왔습니다 is 전화. So it has a different subject from the preceding clause.
See Chapter: Expressing Completion, Section 01 -았/었다가 here.
>> Expressing Mid-Action:
01 -는 길에
02 -다가
>> Full of Intermediate grammar: Click here