31. Must / Should / Have to

Korean Obligation Sentence

English has ‘must do’, ‘should’, ‘have to’. However, They all are same in Korean. Korean language has only one modal verb for describing obligation in a sentence. Technically, Korean language doesn’t have ‘must’ or ‘should’. So yeah… maybe there isn’t many things to teach today. (I wrote this before I finish the lesson and I was super wrong)

한국어에는 must가 없다는 것을 알아야 해요
You should know there is no must in Korean language

해야 돼요 vs 해야 해요

Koreans use 2 phrases, 해야 돼요 and 해야 해요, to express obligation. Both doesn’t make big differences but I asked it to The National Institute of the Korean Language and they answered ‘해야 해’ has a stronger nuance that the subject is willing to.

As a Korean, I can say 해야돼요 is much more common in conversations and sounds a bit casual.

샤워 해야 해요
I have to take a shower

샤워 해야 돼요
I have to take a shower

-야한다 with 하다 verb

I think the obligation mood with 하다 verb is most common than others. It works same to other conjugations so it won’t be much confusing if you learned other lessons with me. if the verb ends with 하다 then the conjugation becomes ‘해야 해요’, otherwise, all will be ‘+어야 해요’ or ‘+아야 해요’.

저는 공부해야돼요
I have to study
= Have to do

오늘 밤엔 저녁에는 배고파야돼요
I have to be hungry tonight
= Have to be

게임해야돼요
I’m going to play a video game
= ‘be going to’. Something it’s more natural as ‘be going to’. You will learn about the details in another lesson

돼요 vs 되요

They are a same word with different spellings. It happens because of conjugations. Even native Koreans are often wrong. I’m not going to teach you when you should use 돼요 or 되요 because it needs a whole lesson. But, I can give you a tip. Just use 되 for everything because it’s less weird than using 돼 for everything. Of course, I’m going to teach you about in another course though.

-야한다 with 이다 verb

-야한다 with 이다 is same to -야한다 with 하다 verb. However, the conjugation changes slightly by a 받침 at the end of word. (It’s same to other conjugations)

여기서 먹여야 돼요
You have to feed them here
= Have to do

강아지여야 해요
It must be a puppy
= Have to be + noun

내일 아침이어야 해요
It should be tomorrow morning
= Have to be + noun

-야한다 with 있다 verb

when 있다 verb is used with -야한다, It loses the meaning of possession a bit but not too much. it’s more natural to translate as ‘do you need something’.

차 꼭 있어야 해요?
Should we really have a car?
= Do we really need a car?
= Have to have / possession

여기 계속 있어야 돼요
We have to keep staying here
= Have to be + location

Adverb 꼭 / 반드시

꼭 and 반드시 are an adverb that is often used with ‘have to’ or Imperative sentences (order). You can translate them as ‘really’, ‘seriously’, ‘must’, ‘never’ but there is no perfect vocabulary for those in English.

꼭 is informal and causal. 반드시 is formal.

여기 꼭 계속 있어야 돼요
We must keep staying here

반드시 여기 계속 있어야 돼요
We must keep staying here