확인하다([hwag-in-ha-da/check]) means to check or confirm. In polite speech, say 확인해요([hwag-in-hae-yo]).
확인했어요([hwag-in-hae-sseo-yo/checked]) is the polite past form. Example: 메일을 확인했어요 (I checked the mail).
확인해야 해요([hwag-in-hae-ya hae-yo/have to check]) means you must check. Example: 지금 확인해야 해요 (I have to check now).
확인하다([hwag-in-ha-da/check]) means "to check". It is used when you verify or confirm information.
1. Daily: “메일을 확인해요 (me-i-reul hwag-in-hae-yo)”
2. Past: 확인했어요([hwag-in-hae-sseo-yo/checked]) checked.
3. Duty: 확인해야 해요([hwag-in-hae-ya hae-yo/have to check]) have to check.
4. Warning: 확인하지 마세요([hwag-in-ha-ji ma-se-yo/don't check]) don't check.
A: What do you check?
B: 메일을 확인해요. B: me-i-reul hwag-in-hae-yo.B: I check the mail.
A: 왜 확인해요? A: wae hwag-in-hae-yo?A: Why do you check?
B: 중요해서 확인해요. B: jung-yo-hae-seo hwag-in-hae-yo.B: I check because it's important. - 확인하다([hwag-in-ha-da/check])
A: Did you check yesterday?
B: 네, 확인했어요. B: ne, hwag-in-hae-sseo-yo.B: Yes, I checked.
A: 뭘 확인했어요? A: mwol hwag-in-hae-sseo-yo?A: What did you check?
B: 여권을 확인했어요. B: yeo-ggwo-neul hwag-in-hae-sseo-yo.B: I checked the passport. - 확인했어요([hwag-in-hae-sseo-yo/checked])
A: When do you have to check?
B: 지금 확인해야 해요. B: ji-geum hwag-in-hae-ya hae-yo.B: I have to check now.
A: 뭘 확인해야 해요? A: mwol hwag-in-hae-ya hae-yo?A: What do you have to check?
B: 비행기 시간을 확인해야 해요. B: bi-haeng-gi si-ga-neul hwag-in-hae-ya hae-yo.B: I have to check the flight time. - 확인해야 해요([hwag-in-hae-ya hae-yo/have to check])
• 확인하다([hwag-in-ha-da/check]) check
- 확인했어요([hwag-in-hae-sseo-yo/checked]) checked
- 확인하고 싶어요([hwag-in-ha-go si-peo-yo/want to check]) want to check
- 확인해야 해요([hwag-in-hae-ya hae-yo/have to check]) have to check
- 확인하지 마세요([hwag-in-ha-ji ma-se-yo/don't check]) don't check