대답하다([dae-dap-ha-da/answer]) means to answer or reply. In polite speech, say 대답해요([dae-dap-hae-yo]).
대답했어요([dae-dap-hae-sseo-yo/answered]) is the polite past form. Example: 질문에 대답했어요 (I answered the question).
대답해야 해요([dae-dap-hae-ya hae-yo/have to answer]) means you must answer. Example: 지금 대답해야 해요 (I have to answer now).
대답하다([dae-dap-ha-da/answer]) means "to answer". It is used when you give a reply to a question.
1. Daily: “질문에 대답해요 (jil-mu-ne dae-dap-hae-yo)”
2. Past: 대답했어요([dae-dap-hae-sseo-yo/answered]) answered.
3. Duty: 대답해야 해요([dae-dap-hae-ya hae-yo/have to answer]) have to answer.
4. Warning: 대답하지 마세요([dae-dap-ha-ji ma-se-yo/don't answer]) don't answer.
A: What do you answer?
B: 질문에 대답해요. B: jil-mu-ne dae-dap-hae-yo.B: I answer the question.
A: 왜 대답해요? A: wae dae-dap-hae-yo?A: Why do you answer?
B: 물어봐서 대답해요. B: mu-reo-bwa-seo dae-dap-hae-yo.B: I answer because they asked. - 대답하다([dae-dap-ha-da/answer])
A: Did you answer yesterday?
B: 네, 대답했어요. B: ne, dae-dap-hae-sseo-yo.B: Yes, I answered.
A: 뭘 대답했어요? A: mwol dae-dap-hae-sseo-yo?A: What did you answer?
B: 질문에 대답했어요. B: jil-mu-ne dae-dap-hae-sseo-yo.B: I answered the question. - 대답했어요([dae-dap-hae-sseo-yo/answered])
A: When do you have to answer?
B: 지금 대답해야 해요. B: ji-geum dae-dap-hae-ya hae-yo.B: I have to answer now.
A: 뭘 대답해야 해요? A: mwol dae-dap-hae-ya hae-yo?A: What do you have to answer?
B: 전화에 대답해야 해요. B: jeon-hwa-e dae-dap-hae-ya hae-yo.B: I have to answer the phone. - 대답해야 해요([dae-dap-hae-ya hae-yo/have to answer])
• 대답하다([dae-dap-ha-da/answer]) answer
- 대답했어요([dae-dap-hae-sseo-yo/answered]) answered
- 대답하고 싶어요([dae-dap-ha-go si-peo-yo/want to answer]) want to answer
- 대답해야 해요([dae-dap-hae-ya hae-yo/have to answer]) have to answer
- 대답하지 마세요([dae-dap-ha-ji ma-se-yo/don't answer]) don't answer