Day 20: Have to, may, must not
Three endings, all built on 돼요 (it works out / it's OK), and they cover obligation and permission completely.
⚠️ And one pair reverses the English logic, exactly the way German's müssen nicht does:
안 가도 돼요 = you don't have to go. 가면 안 돼요 = you must not go.
Two similar-looking sentences, opposite meanings. Section 4.
1. ★★ -아/어야 돼요 — "have to"
### Take the 해요 form, drop 요, add 야 돼요.
| Verb | 해요 form | + 야 돼요 |
|---|---|---|
| 가다 | 가요 | 가야 돼요 |
| 먹다 | 먹어요 | 먹어야 돼요 |
| 하다 | 해요 | 해야 돼요 |
| 자다 | 자요 | 자야 돼요 |
| 배우다 | 배워요 | 배워야 돼요 |
| 있다 | 있어요 | 있어야 돼요 |
★ Every ending from here to Day 26 is built the same way — start from the 해요 form. That is why Day 6 mattered: the 해요 form is the hub the rest of the language hangs off.
지금 가야 돼요. — I have to go now.한국어를 공부해야 돼요. — I have to study Korean.내일 일찍 일어나야 돼요. — I have to get up early tomorrow.여권이 있어야 돼요. — You need to have a passport.
돼요 or 해요?
-아/어야 해요 is equally correct. ★ 돼요 is more common in speech, 해요 slightly more formal or written. Use 돼요 and recognise both.
2. ★ -아/어도 돼요 — "may, it's OK to"
### Same 해요 stem, + 도 돼요.
| 가도 돼요. | You may go |
|---|---|
| 먹어도 돼요. | You may eat it |
| 여기 앉아도 돼요? | May I sit here? |
| 사진 찍어도 돼요? | ★ May I take a photo? |
| 들어가도 돼요? | May I go in? |
| 이거 입어 봐도 돼요? | Can I try this on? (Day 18) |
★ This is the polite way to ask permission for anything, and 사진 찍어도 돼요? is the one to have ready — museums, shops, restaurants, someone's food.
Answering: 네, 돼요. (yes, that's fine) · 네, 그럼요. (of course) · 아니요, 안 돼요. (no, you can't)
★ 돼요 / 안 돼요 on its own is a complete answer — you have already used it as 카드 돼요? on Days 12 and 17.
3. ★ -(으)면 안 돼요 — "must not"
### Vowel stem → -면 안 돼요 · Batchim stem → -으면 안 돼요
| 가면 안 돼요. | You must not go |
|---|---|
| 먹으면 안 돼요. | You must not eat it |
| 여기 주차하면 안 돼요. | You can't park here |
| 사진 찍으면 안 돼요. | No photos |
| 담배 피우면 안 돼요. | No smoking |
(★ -(으)면 on its own means if / when — 시간이 있으면 (if you have time). Day 28 covers it properly; today it arrives inside this fixed shape.)
On signs
| 금지 | prohibited |
|---|---|
| 출입금지 | no entry |
| 촬영금지 | no photography |
| 주차금지 | no parking |
| 금연 | no smoking |
4. ⚠️★ The pair that reverses
### 안 ~아/어도 돼요 = you DON'T HAVE TO### ~(으)면 안 돼요 = you MUST NOT
| 안 가도 돼요. | You don't have to go | ✅ free either way |
|---|---|---|
| 가면 안 돼요. | You must not go | ⛔ prohibited |
| 안 먹어도 돼요. | You don't have to eat it | |
| 먹으면 안 돼요. | You must not eat it |
★ English "don't have to" and "must not" are far apart in meaning and close in shape — and Korean is the same. Telling a friend 가면 안 돼요 when you meant 안 가도 돼요 is a genuinely bad thing to get wrong.
★ The way to hold it: -도 돼요 is permission (with 안, permission not to).-면 안 돼요 is prohibition. If you see 면, it is a ban.
The full set, in one place
| 가야 돼요 | I have to go |
|---|---|
| 안 가도 돼요 | I don't have to go |
| 가도 돼요 | I may go |
| 가면 안 돼요 | I must not go |
| 못 가요 | I can't go (Day 19) |
| 안 가요 | I'm not going (Day 6) |
★ Six shapes, one verb. Read the column out loud twice — this table is the whole day.
5. Dialogue
Alex: 저기요, 여기 사진 찍어도 돼요?직원: 아니요, 여기에서는 찍으면 안 돼요. 저쪽은 괜찮아요.Alex: 아, 알겠어요. 그럼 가방은요? 들고 가도 돼요?직원: 큰 가방은 안 돼요. 여기 맡기셔야 돼요.Alex: 네. 돈 내야 돼요?직원: 아니요, 안 내도 돼요. 무료예요.Alex: 감사합니다. 아, 몇 시까지예요?직원: 여섯 시까지요. 여섯 시 전에 나오셔야 돼요.Alex: 네, 알겠습니다. 신발은 벗어야 돼요?직원: 아니요, 안 벗어도 돼요.Alex: 네, 감사합니다!
★ All four in one conversation, and the contrast is explicit:찍으면 안 돼요 (banned) vs 안 내도 돼요 (not required) vs 맡기셔야 돼요 (required) vs 안 벗어도 돼요 (not required).★ Note -셔야 돼요 — the honorific -시- inside the ending, because the staff member is raising the customer. Recognise it, don't produce it yet.
6. Exercises
A. -아/어야 돼요 — "have to".
- 가다 2. 먹다 3. 하다 4. 자다 5. 공부하다
B. -아/어도 돼요? — "may I?"
- 앉다 2. 먹다 3. 사진 찍다 4. 들어가다
C. -(으)면 안 돼요 — "must not".
- 가다 2. 먹다 3. 주차하다 4. 담배 피우다
D. ⚠️★ Which one?
- You don't have to come. → 안 오___ 돼요.
- You must not come. → 오___ 안 돼요.
- You have to come. → 와___ 돼요.
- You may come. → 와___ 돼요.
E. Translate.
- I have to go now.
- May I take a photo?
- You can't park here.
- You don't have to pay.
- I have to get up early tomorrow.
F. Read the sign.
- 출입금지 2. 촬영금지 3. 금연 4. 주차금지
G. ⚠️ Fix the mistake.
- 가야 해요 돼요.
- 사진 찍어도 안 돼요. (meaning: you must not)
- 안 가면 돼요. (meaning: you don't have to go)
- 먹야 돼요.
Answers
A. 1. 가야 돼요 2. 먹어야 돼요 3. 해야 돼요 4. 자야 돼요 5. 공부해야 돼요 B. 1. 앉아도 돼요? 2. 먹어도 돼요? 3. 사진 찍어도 돼요? 4. 들어가도 돼요? C. 1. 가면 안 돼요 2. 먹으면 안 돼요 3. 주차하면 안 돼요 4. 담배 피우면 안 돼요 D. 1. 안 오아도 → 안 와도 돼요 2. 오면 안 돼요 3. 와야 돼요 4. 와도 돼요 E. 1. 지금 가야 돼요. 2. 사진 찍어도 돼요? 3. 여기 주차하면 안 돼요. 4. 돈 안 내도 돼요. 5. 내일 일찍 일어나야 돼요. F. 1. no entry 2. no photography 3. no smoking 4. no parking G. 1. 가야 돼요 (or 가야 해요 — pick one) 2. 찍으면 안 돼요 3. 안 가도 돼요 4. 먹어야 돼요 — start from the 해요 form 먹어요
7. Today's 10 sentences (flashcards)
- 지금 가야 돼요. — I have to go now
- 한국어를 공부해야 돼요. — I have to study Korean
- 내일 일찍 일어나야 돼요. — I have to get up early tomorrow
- 사진 찍어도 돼요? — May I take a photo?
- 여기 앉아도 돼요? — May I sit here?
- 네, 돼요. — Yes, that's fine
- 아니요, 안 돼요. — No, you can't
- 여기 주차하면 안 돼요. — You can't park here
- 안 가도 돼요. — You don't have to go
- 담배 피우면 안 돼요. — No smoking
8. 📲 Upload to LangNote
Upload section 4 (the six-shape table) and section 7 → study language Korean.
| Mission | What to do with it today |
|---|---|
| 🎧 Podcast | The dialogue — all four shapes appear, contrasted |
| ✍️ Dictation | Today's key mission. -도 돼요 and -면 안 돼요 differ by two syllables and reverse the meaning |
| 🗣 Shadowing | The six-shape table with one verb, out loud, five times |
| 🎭 Role-play | Ask permission for five things — photos, sitting, entering, trying on, paying by card |
| 📖 Vocab | ★ Enter 안 가도 돼요 / 가면 안 돼요 as one card, so the contrast never separates |
★ Tomorrow is the week 3 review — and week 3 was the endings week. Bring your Day 14 numbers.
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