여행하다([yeo-haeng-ha-da/travel]) means go on trip, go journey, visit place. In polite speech, say 여행해요([yeo-haeng-hae-yo]).
여행했어요([yeo-haeng-hae-sseo-yo/traveled]) is the polite past form. Example: 작년에 제주도에 여행했어요 (I traveled to Jeju last year).
여행해야 해요([yeo-haeng-hae-ya hae-yo/have to travel]) means must go on trip. Example: 다음 달에 여행해야 해요 (I have to travel next month).
여행하다([yeo-haeng-ha-da/travel]) means "to travel". It is used when you go on trip, go journey.
1. Daily: “어디로 여행해요? (eo-di-ro yeo-haeng-hae-yo)”
2. Past: 여행했어요([yeo-haeng-hae-sseo-yo/traveled]) traveled.
3. Duty: 여행해야 해요([yeo-haeng-hae-ya hae-yo/have to travel]) have to travel.
4. Warning: 여행하지 마세요([yeo-haeng-ha-ji ma-se-yo/don't travel]) don't travel.
A: Where do you travel to?
B: 제주도로 여행해요. B: je-ju-do-ro yeo-haeng-hae-yo.B: I travel to Jeju.
A: 제주도로 여행해요? A: je-ju-do-ro yeo-haeng-hae-yo?A: You travel to Jeju?
B: 네, 제주도로 여행해요. B: ne, je-ju-do-ro yeo-haeng-hae-yo.B: Yes, to Jeju. - 여행하다([yeo-haeng-ha-da/travel])
A: Did you travel?
B: 네, 여행했어요. B: ne, yeo-haeng-hae-sseo-yo.B: Yes, I traveled.
A: 어디로 여행했어요? A: eo-di-ro yeo-haeng-hae-sseo-yo?A: Where did you travel to?
B: 부산에 여행했어요. B: bu-san-e yeo-haeng-hae-sseo-yo.B: I traveled to Busan. - 여행했어요([yeo-haeng-hae-sseo-yo/traveled])
A: When do you have to travel?
B: 다음 주에 여행해야 해요. B: da-eum ju-e yeo-haeng-hae-ya hae-yo.B: I have to travel next week.
A: 다음 주에 여행해야 해요? A: da-eum ju-e yeo-haeng-hae-ya hae-yo?A: Next week?
B: 네, 다음 주에 여행해야 해요. B: ne, da-eum ju-e yeo-haeng-hae-ya hae-yo.B: Yes, next week. - 여행해야 해요([yeo-haeng-hae-ya hae-yo/have to travel])
• 여행하다([yeo-haeng-ha-da/travel]) travel
- 여행했어요([yeo-haeng-hae-sseo-yo/traveled]) traveled
- 여행하고 싶어요([yeo-haeng-ha-go si-peo-yo/want to travel]) want to travel
- 여행해야 해요([yeo-haeng-hae-ya hae-yo/have to travel]) have to travel
- 여행하지 마세요([yeo-haeng-ha-ji ma-se-yo/don't travel]) don't travel