Learn Hardcore Korean: ellibeiteoga gojang naseo samcheungkkaji georeo ollagaya haeyo. - The elevator is broken, so I have to walk up to the third floor.

가 is the subject particle. It marks 엘리베이터 as the grammatical subject of the clause “고장 나서.” Korean nouns generally require particles like 이/가 or 은/는 to show their role in the sentence.

What does 고장 나다 mean, and why is there no particle between 고장 and 나다?

The compound 고장 나다 means “to break down.” Here 고장 (“a breakdown, fault”) combines directly with the verb 나다 (“to occur, happen”) with no additional particle. It’s a fixed noun-verb compound acting as a single intransitive verb.

Why is 고장 나서 used, and what does -아서/어서 indicate?

The connective ending -아서/어서 attaches to a verb stem to show cause or reason. After dropping “다” from 고장 나다, you get 고장 나 + 서 = 고장 나서, meaning “because it broke down” or “so it broke down,” linking the reason to the next action.

Why do we say 삼층 instead of 세 층 when counting floors?

Floor counters like 층 use Sino-Korean numerals (일, 이, 삼, 사…). Therefore you say 삼층 for “third floor.” Mixing the native Korean number 세 with a Sino-Korean counter (층) is not standard.

What does 까지 mean in 삼층까지?

The postposition 까지 means “up to” or “until.” In 삼층까지, it indicates “as far as the third floor” or “up to the third floor.”

Why is the phrase 걸어 올라가야 해요 used? Could we just say 올라가야 해요?

걸어 올라가다 is a compound verb combining 걷다 (“to walk”) with 올라가다 (“to go up”), so it means “to walk up.” If you said only 올라가야 해요, it would mean “I have to go up” without specifying that you’re walking. The compound form emphasizes walking upstairs.

Could I say 걸어서 올라가야 해요 instead of 걸어 올라가야 해요? What’s the difference?

Yes. 걸어서 is the adverbial form of 걷다 (“on foot, by walking”), followed by 올라가야 해요. 걸어 올라가다 is a fixed compound verb. Both convey “have to walk up,” and the choice is mostly stylistic—adverb+verb versus a single compound verb.

What does -아/어야 해요 express in 걸어 올라가야 해요?

The ending -아/어야 해요 expresses obligation, equivalent to “have to” or “must” in English. Attached to 걸어 올라가다, it yields 걸어 올라가야 해요, “(I) have to walk up.”

Why is there no explicit “I” in the second clause “걸어 올라가야 해요”?

In Korean, subjects (and objects) are often omitted when they’re clear from context. Here, 걸어 올라가야 해요 implicitly means (제가) 걸어 올라가야 해요, “I have to walk up,” because the speaker is understood as the one performing the action.