Time and Reason: -어/아서
Time to talk about a very basic Korean grammar expression you have probably seen everywhere: -어/아서. You can use this grammar pattern for both expressing time, reason or cause. It is pretty nifty expression and you most likely seen it first in expressions such as 만나서 반갑습니다. Let’s take a closer look.
First we’ll talk about the major use of the Korean grammar pattern -어/아서. That use is, of course, expressing reason or cause of something. It is a very nifty expression and you can expect using it very often. So I guess what I am trying to say: make sure you commit this expression to your memory. When you translate a sentence using -어/아서 in this way, you can translate the expression as “so” or “because of” or even “to”. Let’s look at an example:
Example: 날씨가 정말 뜨거워서 아이스크림을 먹고 싶네요.
Translation: The weather is so hot you really want to eat a lot of ice cream.
Time Expression -어/아서
However, you can also use the pattern -어/아서 in time expressions. As you can very well guess the meaning when used as such it totally different. When you use it as a time expression, the pattern expresses that the action of the second clause (the part after -어/아서) happens after the first clause. Furthermore the actions are so closely related that the second part couldn’t have happened without the first action having occurred in the first place. Let’s look at an example.
Example: 학생은 사과를 깎아서 먹었어요.
Translation: The student peeled the potato and ate it.
When the pattern is used as a time expression, you translate it as “(in order) to” or “and”.
How To Use
Using the expression -어/아서 isn’t that hard, but it does have a few rules you have to keep in mind. Furthermore some rules are unique to the two separate ways to use the expression. I suggest you take a few to make sure you’ve committed those differences you your memory.
First let’s talk about the conjugation as that is the easiest set of rules because you have seen it a hundred times. As you have guessed, the pattern -어/아서 adheres to the same rules you have mastered for the Korean present tense. Yet, for good measure we’ll repeat them here just for this expression:
- When the verb stem has either ㅏ or ㅗ in its final syllable, you use -아서.
- If not, you use the ending -어서.
- For 하다 verbs, you use 해서.
- However, 이다 has to forms: 이어서 and 이라서. 이라서 is used in conversations only.
The second aspect you need to keep in mind about -어/아서 are the use of tense markers. The tense markers (e.g. -었/았/했-) cannot be used with 어/아서. Sentence with this pattern express their tense in the second clause. So when the second clause is set in the past, the first clause is also in the past.
A third remark you need to keep in mind is that sentences with and -어/아서 clause can never be either imperative or propositive. For these sentences you will have to use another clause to express reason or cause.
Lastly there is a slight asterisk I need to make that is exclusive to its use as a time expression. When you want to use it as such the subject of the first and the second clause needs to be the same. They cannot be different when using -어/아서.
-어/아서 VS -(으)니까
Perhaps you remember the Korean grammar expression -(으)니까 and seen that the pattern and this -어/아서 look eerily similar. They are very similar and have the same meaning. However, their use is different. Things you can do with one pattern, you cannot do with the others. Let’s go over the differences.
Difference 1: Imperative and Propositive
As was already mentioned sentences with the pattern -어/아서 cannot be either imperative (such as -(으)세요) or propositive (such as -(으)ㄹ까요). For these sentences you will have to use the expression -(으)니까.
Example: 다리가 아프니까 지하철을 탈까요?
Translation: My legs hurt so shall we take the subway?
Difference 2: Tense Markers
Tense markers such as -었/았/했- and -겠- are never used before -어/아서. The tense in these sentences is always expressed in the subsequent clause. So both clauses always have the same tense However, when the clauses need to have different tenses you will have to use -(으)니까 as that one can use tense markers.
Example: 한국에서 살았으니까 저는 한식을 잘 요리해요.
Translation: I can cook Korean food well because I lived in Korea.
Difference 3: Kinds of reason
There is also a difference in the kind of reason you express with either of these reason expressions. The pattern -어/아서 expresses a general reason. However, -(으)니까 you use when the reason is subjective or when you are providing the basis for something in particular. Generally, it is also used when the already knows about the topic that is being discussed.
Example: -왜 늦었어요? -길이 막히니까 늦었어요.
Translation: -Why were you late? -The roads are congested so I was late.
Difference 4: Idiomatic Use – Greetings
There are some common expressions you use with verbs/adjectives such as 반갑다, 고맙다, 감사하다 and 미안하다. For these expressions you can only use -어/아서, never -(으)니까.