Learn Hardcore Korean: i beoteuneul nureul jul ara? - Do you know how to press this button?

이: this
버튼: button
-을: object marker
누르-: verb stem “press”
-ㄹ: attributive ending attaching the verb to a following noun
줄: bound noun meaning “way/knack/knowledge (of how)”
알-: “to know”
-아?: casual question ending Overall: “[Do you] know the way/how to press this button?”

What does the construction -ㄹ/을 줄 알다 mean?

It means “to know how to [do something].” You attach -ㄹ/을 to the verb stem, add the bound noun 줄, then 알다. Examples:

읽을 줄 알아요 = I know how to read.
수영할 줄 알아요 = I know how to swim.

Why is it 누를 and not 눌러 or 누르다?

Because 줄 is a noun, the verb before it must be in the attributive (modifier) form:

Verb stem + -ㄹ/을
- 줄. For 누르다 (stem 누르-), add -ㄹ → 누를.
  눌러 is the connective/imperative form (used for commands or linking), and 누르다 is the dictionary form; neither can modify 줄 directly.

Is 누르다 irregular? Why is it 눌러 elsewhere but 누를 here?

Yes, 누르다 is 르‑irregular. When you add -아/어, the 르 triggers an extra ㄹ and the vowel changes: 눌러(요).
But with the attributive -ㄹ, you simply add -ㄹ to the stem: 누르- + ㄹ → 누를. So both 눌러 and 누를 are correct in their respective contexts.

Can I drop the object marker -을 and say 이 버튼 누를 줄 알아?

Yes. In casual speech, object particles (을/를) are often dropped when the meaning is clear. Keeping 을 is slightly clearer or more careful; dropping it sounds very natural in conversation.

What’s the difference between -줄 알다 and -수 있다?

-줄 알다 emphasizes knowing the method/skill: “know how to.”
-수 있다 emphasizes ability/possibility: “can/is able to.” In many everyday cases (like pressing a button), both are acceptable:
이 버튼을 누를 줄 알아요?
이 버튼을 누를 수 있어요? If you mean permission/possibility, prefer forms like 눌러도 돼요? (“Is it okay to press it?”).

Is this sentence polite? How do I make it more polite or more formal?

The given sentence (… 알아?) is casual. Politer options:

Polite: 이 버튼을 누를 줄 알아요?
Polite with honorific to the listener: 이 버튼을 누를 줄 아세요?
Formal: 이 버튼을 누를 줄 아십니까? Using 아세요/아십니까 shows respect toward the listener.

Who is the subject? Should I add 너 or 당신?

Korean often omits the subject when it’s obvious; here it’s understood as “you.”

You can add 너 in very casual contexts: 너 이 버튼을 누를 줄 알아?
Avoid 당신; it’s rarely used for “you” in normal conversation and can sound confrontational. Use names/titles instead (e.g., 선생님, … 아세요?).

How do I pronounce it naturally?

Read smoothly with a rising intonation at the end:

이 버튼을 누를 줄 알아? → [i beo-teun-eul nu-reul jul a-ra?] Linking happens across word boundaries; 알아 has a tapped/flapped ㄹ sound between vowels.

What’s the negative or a natural way to say “I don’t know how”?

Casual: 몰라 (from 모르다, which is irregular).
Polite: 몰라요 or a softer 잘 모르겠어요 (“I’m not sure/don’t really know”).

I’ve seen -줄 알았다 used as “I thought (that) …”. Is that related?

Yes. -줄 알다 has another meaning in the past: “to think/assume that …”

네가 올 줄 알았어 = I thought you would come.
With ability, -줄 알다 in the present is “know how to,” but in the past it can be ambiguous. Context clarifies whether it means past knowledge of a skill or a mistaken assumption.

Why is there a space before 줄 and another before 알아?

줄 is a dependent noun, so it’s written as a separate word from the verb modifier: 누를 줄. And 알아 is the next verb, so 줄 알아 is also spaced. Correct spacing: 누를 줄 알아.

Is this a request to press the button right now?

Not directly. It asks about the listener’s ability/knowledge. To request action, use:

Casual: 이 버튼 좀 눌러 줄래? / 이 버튼 좀 눌러 줘.
Polite: 이 버튼 좀 눌러 주세요.

Can I use 법 instead of 줄?

Yes, with a slight nuance difference. -는 법 means “the method/way (of doing).”

이 버튼을 누르는 법 알아? = Do you know the method of pressing this button?
This can sound a bit more like knowing instructions. -줄 알다 feels more like having the skill.

What does 이 add? Could I use 그 or 저 instead?

이 = this (near the speaker)
그 = that (near the listener or previously mentioned)
저 = that (far from both) Use the one that matches the button’s location or prior mention: 이/그/저 버튼.

How would I answer briefly?

Yes (casual/polite): 응, 알아. / 네, 알아요. or 네, 할 줄 알아요.
No (casual/polite): 아니, 몰라. / 아니요, 몰라요. or 아니요, 잘 몰라요.