And then)¶

In Unit 2, we learned how to link sentences using -고 (and). In this unit, we will learn another extremely important linking structure: -아/어/여서.

This structure has two main meanings: 1. Reason/Cause: "Because [A], [B] happens" 2. Sequential Action: "[A] happens, and then [B] happens (and they are closely related)"

How to Conjugate¶

The conjugation rule for -아/어/여서 is exactly the same as the present tense ending (-아/어/여요), you just replace "요" with "서".

If the last vowel of the stem is 아 or 오: Add -아서
- 가다 -> 가 + 아서 = 가서
- 오다 -> 오 + 아서 = 와서
If the last vowel is NOT 아 or 오: Add -어서
- 먹다 -> 먹 + 어서 = 먹어서
- 읽다 -> 읽 + 어서 = 읽어서
If the verb ends in 하다: Change to 해서
- 공부하다 -> 공부해서

Usage 1: Reason ("Because")¶

When the first part of the sentence is the reason for the second part.

비가 와서 집에 있었어요. (It rained, so I stayed home. / Because it rained, I stayed home.)
배가 아파서 병원에 가요. (My stomach hurts, so I am going to the hospital.)
너무 비싸서 안 샀어요. (It was too expensive, so I didn't buy it.)

Important Note: You cannot use past tense or future tense markers before -아/어/여서. The tense is only shown at the very end of the sentence. (e.g., 비가 왔어서 is WRONG. 비가 와서 is RIGHT). Also, you cannot use imperative (do this) or propositive (let's do this) endings with -아/어/여서.

Usage 2: Sequential Action ("And then")¶

When you do one action, and that leads directly into the next action. The two actions must be tightly connected (usually sharing the same subject and location/context).

공원에 가서 책을 읽었어요. (I went to the park and then read a book.) (You couldn't read the book if you didn't go to the park first. The actions are linked.)
친구를 만나서 밥을 먹었어요. (I met a friend and then we ate food.) (You ate food together with the friend you just met.)

Difference between -고 and -아/어/여서 for sequences:¶

-고: Simple list of actions. (I ate dinner, and I watched TV).
-아/어/여서: A logical progression or prerequisite. (I went to the cafe, and then drank coffee there.)