Must/Have To (-아/어야 하다)

-아/어야 하다 expresses that something must be done. It is equivalent to English 'must' or 'have to'. The choice between -아야 and -어야 follows standard vowel harmony rules: use -아야 after stems with ㅏ or ㅗ, and -어야 after all other vowels. 하다 verbs become 해야 하다.

This pattern can be conjugated in various tenses: 가야 해요 (must go, present), 가야 했어요 (had to go, past). You can also replace 하다 with 되다 for a softer nuance: 가야 돼요 sounds slightly less forceful than 가야 해요.

This is one of the most practical grammar patterns for daily life. You will use it constantly when talking about schedules, responsibilities, and requirements. It often appears in combination with other patterns like -기 전에 (before) or -(으)ㄹ 때 (when).