Learn Hardcore Korean: bame honja geotneun geon wiheomhae. - It’s dangerous to walk alone at night.

It’s the contraction of 것은 (것 + topic marker 은). So 걷는 건 literally means “as for walking.” This sets “walking (alone at night)” as the topic of the sentence in a casual tone. In everyday speech, 것 also shortens to 거, so you’ll hear forms like 걷는 건 instead of the full 걷는 것은.

What’s the difference between 걷는 건 위험해 and 걷는 게 위험해?

건 = topic (것은): “As for walking…, it’s dangerous.” Often slightly contrastive or framing.
게 = subject (것이): “Walking… is dangerous.” More neutral/factual focus. Both are correct here; 게 can sound a bit more matter-of-fact, while 건 can imply contrast (e.g., “At night it’s dangerous, but in the day it isn’t”).

What grammar is 걷는?

It’s the present adnominal (relative) form of 걷다 modifying 것. 걷는 것 = “the act of walking.” It often corresponds to English -ing (gerund) but is a clause that modifies a noun, not a progressive tense.

Why isn’t it 걸는 if 걷다 is ㄷ-irregular?

ㄷ-irregular verbs change ㄷ to ㄹ only before vowel-initial endings. -는 begins with a consonant, so the stem keeps ㄷ: 걷- + -는 → 걷는. Compare: 걸어요 (polite present), 걸을 때 (when [someone] walks), but 걷는 사람 (a person who walks).

Can I use 걷기 instead of 걷는 것?

Yes: 밤에 혼자 걷기는 위험해(요) is natural. -기 feels more like naming an activity (a verbal noun), while -는 것 is a fuller clausal noun that takes modifiers more freely. In this sentence, either works.

Is 위험해 polite enough?

위험해 is casual (to friends, younger people). Polite: 위험해요. Formal: 위험합니다 (announcements, writing). The dictionary form 위험하다 isn’t used as a standalone statement in conversation.

Why is there no subject like “it” or “you”?

Korean often drops subjects when clear. Here, 걷는 건 (walking) is the topic, and the predicate 위험해 completes the thought. If you want to address the listener directly, you could say 밤에 혼자 걸으면 위험해요 (“If you walk alone at night, it’s dangerous”).

Why not use 이다 after 위험?

Because 위험하다 is a descriptive verb (adjective) in Korean. You say 위험해(요), not 위험이에요, to mean “is dangerous.”

Why is it 밤에 and not 밤에서?

-에 marks time points, so 밤에 = “at night.” -에서 marks the place where an action happens (e.g., 길에서 걷다 “walk on the road”). You can combine them: 밤에 길에서 혼자 걷는 건 위험해요. Adding 는 for contrast (밤에는) highlights “at night” in contrast to other times.

Does 혼자 mean “by myself”? How does it differ from 혼자서 or 홀로?

혼자: alone, by oneself (neutral, most common).
혼자서: emphasizes “by oneself” (a touch stronger).
홀로: literary/poetic. All fit here; 혼자 is the most natural.

Is the word order fixed? Could I say 혼자 밤에 걷는 건?

The neutral order is time → manner → verb: 밤에 혼자 걷는 건. 혼자 밤에 걷는 건 is understandable but less natural; 밤에 혼자 sounds smoother. You can also say 혼자 밤길을 걷는 건 위험해요 (using 밤길, “night road”).

How is 걷는 건 pronounced?

걷는 undergoes assimilation: it’s pronounced roughly [건는] (geonneun). So 걷는 건 sounds like [건는 건] (geonneun geon). 위험해 is [wi-heom-hae], 밤에 is [ba-me].

Is it okay to write 걷는건 without a space?

Standard spacing is with a space: 걷는 건 위험해. Writing 걷는건 is common in casual texting but is nonstandard in formal writing.

How do I say “Don’t walk alone at night”?

Negative imperative: 밤에 혼자 걷지 마요 (polite) or 걷지 마 (casual). Stronger/safer: 밤에는 혼자 다니지 마세요.

How do I make it past or future?

Change the adjective: 위험했어/위험했어요 (was dangerous), 위험할 거야/위험할 거예요 (will be dangerous). The topic phrase 밤에 혼자 걷는 건 stays the same.

Why use 걷다 and not 가다?

걷다 specifically means “to walk (on foot),” which the sentence warns about. 가다 is “to go” (no specific means). If you mean going somewhere alone at night in general: 밤에 혼자 가는 건 위험해요.

Can I say the fully formal version?

Yes: 밤에 혼자 걷는 것은 위험합니다. That’s the uncontracted, formal style suitable for notices or public announcements.