Separate competing effort from a general cause

Both 공부하느라 못 잤어요 and 피곤해서 못 갔어요 can contain “because” in an English translation. Yet they tell different stories. In the first, studying took the time you might have spent sleeping. In the second, tiredness explains why you did not go. Thinking about that difference makes the Korean ending easier to choose.

We will compare two reasons for a similar result, then look at the person doing the action and the kind of cause being described. Read each Korean sentence as a small situation, rather than choosing an ending from the English translation alone.

Build -느라 and -아/어서 accurately

With -느라, picture one person occupied with an action that interferes with something else. 가방을 찾느라 전화를 못 받았어요 means “I could not answer the phone because I was looking for my bag.” The search and the missed call belong to the same person, and the search explains what kept that person busy.

The shortened -느라 and the fuller -느라고 express the same basic connection in these examples. Attach the ending to an action-verb stem: 찾다 becomes 찾느라, and 공부하다 becomes 공부하느라. For a straightforward learner example, keep the person doing the first action the same as the person experiencing the result.

Preserve the unintended-result nuance

Compare that with 길이 막혀서 늦었어요, “I was late because traffic was bad.” Traffic is a condition that caused the delay, rather than an activity that the speaker spent time doing. -아/어서 gives you the broader cause connection here. A disappointing result by itself is not enough to select -느라.

The broader -아/어서 connection can also describe a sequence in other sentences, so read the complete example. Here, 비가 와서 못 갔어요 gives rain as the reason for not going. It does not describe the speaker spending effort on an activity.

Compare two reasons in one situation

The speaker missed the phone while searching for a lost bag. 찾느라 presents the search as the competing activity. The follow-up 지금은 찾았어요? asks whether the bag has now been found; the reply says a report was filed, so the problem is still unresolved.

To practise a variation, imagine preparing for an exam instead. 시험공부를 하느라 휴대폰을 못 봤어요 keeps the same person and the same missed-phone result, while changing the activity that occupied the speaker.

Do not force -느라 onto every negative result

Ask two questions before using -느라: “What was the person busy doing?” and “What did that activity prevent or delay?” If you can answer both with the same person in mind, you have the shape of the examples in this lesson.

If the cause is weather, illness, or a traffic condition, begin with the broader -아/어서 examples. A sentence such as 피곤해서 못 갔어요 does not need an invented activity to explain the result. This is why translating both endings as “because” leaves out information you need in Korean.

Correct likely misunderstandings

A useful correction is 비가 와서 못 갔어요. Treating rain as a -느라 activity would miss the relationship this lesson teaches. Likewise, using -느라 does not decide whether an explanation is a convincing excuse; it tells the listener how the speaker connects the two actions.

Read an original six-part analysis

The final two Korean lines explain the difference shown in the dialogue. Read them alongside the English explanation, then return to 찾느라 in the second line.

Try it in a familiar situation

A small listening check

References and useful next steps

• Korean–English Learners’ Dictionary — Check meanings, usage labels, conjugated examples and human recordings for the lesson vocabulary.
• National Institute of Korean Language — Reference for standard Korean usage and grammar.
• Review Korean word order before comparing subjects across two clauses.

Examples and dialogues are original. Reviewed October 1, 2026. Found a mistake? Send a correction.