-것 같다 — three tenses, one big role
-것 같다 literally means 'it seems like ~ thing / looks like ~ thing'. It's how Korean expresses inference, opinion-with-hedge, and probability. Three tense flavors based on the modifier you put before 것: -는 것 같다 = 'looks like / seems like (now)' (present action); -(으)ㄴ 것 같다 = 'looks like ~ happened / seems like (past or adjective)'; -(으)ㄹ 것 같다 = 'probably will / looks like will'. 비가 오는 것 같아요 = 'It looks like it's raining.' 비가 온 것 같아요 = 'It looks like it rained.' 비가 올 것 같아요 = 'It looks like it'll rain.' Korean uses this constantly to soften opinions ('I think...') and to make polite indirect statements. It's one of the most-used B1 patterns — master it and your Korean immediately sounds more natural.
Form by tense — action verbs
Present (looks like ~ is happening): -는 것 같다. 가다 → 가는 것 같아요 = 'It seems he's going.' 먹다 → 먹는 것 같아요 = 'It looks like he's eating.' Past (looks like ~ happened): -(으)ㄴ 것 같다. 가다 → 간 것 같아요 = 'It looks like he went.' 먹다 → 먹은 것 같아요 = 'It looks like he ate.' Future / probable (looks like ~ will happen): -(으)ㄹ 것 같다. 가다 → 갈 것 같아요 = 'I think he'll go / It seems he'll go.' 먹다 → 먹을 것 같아요 = 'I think he'll eat.' Speech contraction: 것 같아요 → 거 같아요, very common informally.
Form by tense — adjectives
Adjectives use -(으)ㄴ 것 같다 for their general/'now' state (since adjectives don't have -는 modifiers): 춥다 → 추운 것 같아요 = 'It seems cold / I think it's cold.' 예쁘다 → 예쁜 것 같아요 = 'I think she's pretty.' For 'probably will be': -(으)ㄹ 것 같다: 추울 것 같아요 = 'I think it'll be cold.' For past state, use the explicit past -았/었던 것 같다 (recollected) or just -았/었을 것 같다 (probably was): 추웠을 것 같아요 = 'I bet it was cold.' For 이다 ('be'), use -인 것 같다: 학생인 것 같아요 = 'I think (he/she) is a student.'
As 'I think' — softener
Korean speakers use -것 같다 much like English speakers use 'I think...' to avoid sounding too direct. Even when you're sure, hedging with -것 같다 sounds politer. 이 음식 맛있어요 ('this food is delicious') vs. 이 음식 맛있는 것 같아요 ('I think this food is delicious'). Both are fine; the second is softer and more deferential, especially with someone whose taste might differ. Use -것 같다 liberally when giving opinions about taste, weather, distance, others' feelings. 그분이 좀 피곤한 것 같아요 = 'He seems a bit tired' is more polite than baldly stating his state.
Inference from evidence
-것 같다 doesn't require visible evidence, but it's most natural when there's some basis for your inference: physical clues, hearsay, a feeling. 하늘이 어두워요. 비가 올 것 같아요 = 'The sky is dark. It looks like it'll rain.' 민지 씨가 안 왔어요. 아픈 것 같아요 = 'Minji didn't come. It seems she's sick.' Compare -나 보다 ('seems like, judging by external evidence', a bit more bookish) and -는 것 같다 (more conversational, evidence-or-opinion). At B1, -것 같다 handles 90% of 'seems' situations.
Common pitfalls
Don't double-tense the modifier. 갔는 것 같아요 is wrong; you use -(으)ㄴ 것 같다 for past: 간 것 같아요. Don't say 갈 것 같았어요 to mean 'I think he went'. -(으)ㄹ 것 같았어요 is past-tense of the verb 같다, meaning 'I thought (then) he'd go.' To say 'I think he went (now)', use 간 것 같아요. Use the right modifier for action vs. adjective. 재미있다 / 맛있다 behave like action verbs: 재미있는 것 같아요, 맛있는 것 같아요. Pure adjectives like 춥다 take -(으)ㄴ: 추운 것 같아요. Don't say 춥는 것 같아요 — that's wrong.
Negation with -것 같다
Two ways: (1) negate the inner verb: 안 가는 것 같아요 = 'It seems he isn't going.' 안 간 것 같아요 = 'It seems he didn't go.' (2) 'doesn't seem' by negating 같다: 갈 것 같지 않아요 = 'It doesn't seem he'll go.' Both are common; the second sometimes sounds more emphatic ('really doesn't seem'). For 'I don't know if...': use -(으)ㄹ지 모르겠어요 (a different pattern). For 'I'm not sure if it's good': 좋은 것 같지 않아요 vs. 좋을지 모르겠어요 — first says 'it doesn't seem good', second says 'I'm not sure if it'll be good'.
