모르다([mo-reu-da/not know]) means you have no information in your head. In polite speech, say 몰라요([mol-la-yo]).
몰랐어요([mol-la-sseo-yo/didn't know]) is the polite past form. Example: 답을 몰랐어요 (I didn't know the answer).
알다([al-da]) means you have information, 모르다([mo-reu-da]) means you have no information. They are opposites.
모르다([mo-reu-da/not know]) means "to not know". It is used when you have no information in your head.
1. Daily: “답을 몰라요 (da-beul mol-la-yo)”
2. Past: 몰랐어요([mol-la-sseo-yo/didn't know]) didn't know.
3. Duty: 몰라야 해요([mol-la-ya hae-yo/have to not know]) have to not know.
4. Warning: 모르지 마세요([mo-reu-ji ma-se-yo/don't say you don't know]) don't say you don't know.
A: Do you not know the answer?
B: 네, 몰라요. B: ne, mol-la-yo.B: Yes, I don't know.
A: 왜 몰라요? A: wae mol-la-yo?A: Why don't you know?
B: 안 배웠어요. B: an bae-wo-sseo-yo.B: I didn't learn it. - 모르다([mo-reu-da/not know])
A: What didn't you know?
B: 답을 몰랐어요. B: da-beul mol-la-sseo-yo.B: I didn't know the answer.
A: 언제 몰랐어요? A: eon-je mol-la-sseo-yo?A: When didn't you know?
B: 어제 몰랐어요. B: eo-je mol-la-sseo-yo.B: I didn't know yesterday. - 몰랐어요([mol-la-sseo-yo/didn't know])
A: What do you have to not know?
B: 비밀을 몰라야 해요. B: bi-mi-reul mol-la-ya hae-yo.B: I have to not know the secret.
A: 왜요? A: wae-yo?A: Why?
B: 깜짝 파티라서요. B: kkam-jjak pa-ti-ra-seo-yo.B: It's a surprise party. - 몰라야 해요([mol-la-ya hae-yo/have to not know])
• 모르다([mo-reu-da/not know]) not know
- 몰랐어요([mol-la-sseo-yo/didn't know]) didn't know
- 모르고 싶어요([mo-reu-go si-peo-yo/want to not know]) want to not know
- 몰라야 해요([mol-la-ya hae-yo/have to not know]) have to not know
- 모르지 마세요([mo-reu-ji ma-se-yo/don't say you don't know]) don't say you don't know