LEARN KOREAN (한국어) [GRAMMAR] #1

~는/은 AND ~이/가 REVISITED (AGAIN)

For example, in the following dialogue:

누가 밥을 먹었어? - Who ate the rice?
내가 밥을 먹었어 - I ate the rice
This could also be shortened to only include the subject:
내가 - "I did", or "me"

Another example:
누가 피자를 만들었어? - Who made the pizza?
내가 만들었어 - I made it (me)

Notice here that just because (in English) somebody asks a "who" question doesn't mean that ~이/가 must be used on the subject. This is only relevant when the speaker is asking "who" the subject was – and not who the object was (in effect, when "who" translates to 누가 and not to 누구").

누가 그녀를 좋아해? - Who likes her?
내가 그녀를 좋아해 - I like her
Notice above the question is asking who the subject is

너는 누구를 좋아해? - Who do you like?
나는 그녀를 좋아해 - I like her
Notice above the question is asking who the object is. The use of "는" on the subject takes the stress off of the subject and "는" just acts as a subject marker.

The same thing can be done with other question words, as long as the question is asking for the subject. For example:

어떤 것이 더 좋아요? - Which one is better?
이것이 더 좋아요 - This one is better

I can't stress enough that all of these nuances are all situational.
A particular sentence with ~는/은 can make sense in one situation, but could be awkward in another situation. That same sentence might be awkward with ~이/가 in one situation, but appropriate in another situation. In some situations, they could be exactly the same. Ask a Korean person to distinguish between the following:

내 친구가 밥을 먹었다
내 친구는 밥을 먹었다

They will tell you that – depending on the situation – they could be exactly the same. It entirely depends on the nuance that the speaker is trying to make.

Before we finish, I would like to organize everything that we've done and try to describe the usages of ~는/은 and ~이/가 very quickly. Notice that I say "try." It is almost impossible to do this in any form, let alone in just a few sentences. Korean people literally write their doctoral theses on this topic. Nonetheless, here we go:

~는/은:
1) To denote a subject of a sentence. For example:
나는 밥을 먹었다 - I ate rice
내 친구는 밥을 먹었다 - My friend ate rice
나는 그녀를 좋아해 - I like her
This may or may not have an overlapped meaning with the following purposes:
2) To compare something. For example:
이 산은 높다 - This mountain is high (but maybe another mountain is low)
사과는 빨갛다. 바나나는 노랗다 - Apples are red. Bananas are yellow.
3) To state a general fact. For example:
로키산은 높다 - The Rocky Mountains are high
여름 날씨는 좋다 - Summer weather is good (nice)
다이아몬드는 딱딱하다 - Diamonds are hard

~이/가:
1) To denote a subject of a sentence. For example:
고양이가 집 뒤에 있다 - The cat is behind the house
This may or may not have an overlapped meaning with the following purposes:
2) To indicate something based on a recent experience/observation. For example:
날씨가 좋다 - The weather is nice!
비가 와요 - It's raining!
사과가 파랗다 - The apple is blue
3) To stress that the subject does the action (or is the adjective). For example:
누가 그녀를 좋아해? - Who likes her?
– 내가 그녀를 좋아해 - I like her
내가 반장이야! - I am the class president!
4) Placed on objects in sentences that are predicated by adjectives. For example:
나는 학교가 싫다 - I don't like school
나는 그것이 좋다 - I like that
나는 펜이 있다 - I have a pen
5) Placed on the object before 아니다 to indicate what something is not. For example:
나는 학생이 아니다 - I am not a student
나는 의사가 아니다 - I am not a doctor
6) Placed on the object predicated by "되다" to indicate what something becomes. For example:
나는 의사가 되고 싶다 - I want to become a doctor
나는 선생님이 되고 싶다 - I want to become a teacher

You also learned about creating passive sentences with verbs that act in the "state" of something. For example:

문이 열려 있다 - The door is open

I told you that you should use ~이/가 on the object that is in the state of something. I can only assume that the purpose of this is what is described in number 2) above. That is, "the door being open" is not some general statement because (obviously) not all doors are open. Rather, the speaker is referring to a particular door in a particular situation that is open, and thus, requires the use of ~이/가. Adding ~는/은 to "문" (or any other object in that situation) would only be acceptable in a comparison situation.

One last time before we put this to bed for a while:
Your understanding of this will progress along with your understanding of Korean in general. I hope you have a better understanding of this through the lessons. However, I know that you will still be confused. Don't worry, that is normal, and I promise your understanding will evolve as you keep progressing with your Korean.

You will continue to be introduced to when it is more appropriate to use either ~는/은 or ~이/가. For now, focus on what we have learned so far.