What is -는 사이(에) Grammar?
The grammar -는 사이(에) is used to indicate that while the main action is in progress, a second action happens. It often focuses on what happened during a gap or short period, often unexpectedly without the subject’s awareness. It means "while, during the time" in English.
- -는 사이(에) → While doing (present/ongoing actions)
- -ㄴ/은 사이(에) → While something happened (past action already finished)
💡 The particle (에) is optional, but it’s often included for clarity.
How to Conjugate -는 사이(에)
Present tense: Verb + -는 사이(에)
- 먹다 → 먹는 사이에 (while eating)
- 공부하다 → 공부하는 사이에 (while studying)
- 자다 → 잔 사이에 (while sleeping)
- 비가 오다 → 비가 온 사이에 (while raining)
When and How to Use -는 사이(에)
1. Use -는 사이에 when the main action is ongoing in the present.제가 잠깐 졸고 있는 사이에 버스가 출발했어요.
→ While I was dozing off for a moment, the bus left.
엄마가 전화를 하고 있는 사이에 아기가 계단에서 내려갔어요.
→ While mom was on the phone, the baby went down the stairs.
2. Use -ㄴ/은 사이에 when the main action already finished in the past.
내가 잠깐 나간 사이에 비가 많이 왔어요.
→ While I was out for a short while, it rained heavily.
대답하지 못한 사이에 핀잔을 받았다.
→ While I couldn't answer, I got scolded.
3. It can also be used with 있다/없다 to indicate “while being somewhere” or “while something exists/doesn’t exist.”
선생님이 교실에 없는 사이에 학생들이 시끄러웠어요.
→ While the teacher wasn’t in the classroom, the students were noisy.
내가 없는 사이에 많이 예뻐졌네요.
→ While I was away, you've gotten a lot prettier.
Differences from Similar Grammar Patterns
| Grammar | Meaning | Key Difference |
|---|---|---|
| -는 동안(에) | While, during | Focuses on the entire period when an action happens. |
| -(으)ㄹ 때 | When, at the time | Refers to a specific moment rather than the whole duration. |
| -는 김에 | While doing, on the occasion of | Suggests doing something extra while already doing another action. |
| -는 중에 | In the middle of doing | Emphasizes the process or ongoing state of an action, not necessarily an unexpected event like -ㄴ/은/는 사이(에). |
| -ㄴ/은/는 사이(에) | While, in the meantime | Focuses on what happened during a gap or period, often unexpectedly. |
Quick Comparison:
Common Mistakes to Avoid
1. Using -는 사이(에) for long-term actions.
- 저는 1년 공부하는 사이에 많은 책을 읽었어요. (Incorrect)
- 저는 1년 공부하는 동안 많은 책을 읽었어요. (Correct)
2. Forgetting tense changes
- Past events must use -ㄴ/은 사이에, not -는 사이에.
Examples of -는 사이(에) in Use
1. 내가 잠깐 자는 사이에 비가 왔어요.→ It rained while I was taking a short nap.
→ My friend called while I was in class.
→ I ate snacks while mom wasn’t in the kitchen.
→ While I was on the phone, the delivery came.
→ While I was out for a short walk, the sun set.
→ While waiting for the bus, it started to rain.
→ While we were having a meeting, important news came in.
→ A thief broke in while I was not home.
→ I did house chores while the baby was sleeping.
→ While my friend went to the bathroom, the bus left.
Practice Sentences
Translation into Korean using -는 사이(에)
1. While I was eating lunch, my phone rang.
2. While I was eating, a friend came up to me and said hello.
3. A lot of work piled up while I was away.
4. While we were talking, the train arrived.
Answers:
1. 점심을 먹는 사이에 전화가 왔어요.
2. 밥을 먹는 사이에 친구가 앞에 와서 인사했어요.
3. 내가 없는 사이에 일이 많이 쌓였어요.
4. 이야기하는 사이에 기차가 도착했어요.
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