Grammar Rule in 30 Seconds
Modal verbs like 'can', 'should', and 'must' change the mood of a sentence without ever changing their own form.
- Never add -s, -ed, or -ing to a modal verb. Example: 'He can swim' NOT 'He cans swim'.
- Always follow a modal with the base verb (no 'to'). Example: 'I must go' NOT 'I must to go'.
- To make a question, just swap the subject and the modal. Example: 'Should I stay?'
Overview
he walks인지 they walk인지 기억해야 하고, did와 does를 걱정해야 하죠. 조동사(Modal verbs)는 여러분의 새로운 절친입니다.-s도 없고, -ed도 없고, 드라마틱한 변화도 없습니다.I go는 사실이지만, I can go는 느낌입니다.can, should, must와 같은 특별한 동사입니다. 능력, 허가, 필요성 등을 표현하죠. 영어에서 가장 빠른 지름길입니다.Can you hear me?는 전형적인 조동사 활용 사례입니다.
Should I post this selfie?도 마찬가지죠. 현대 생활 어디에나 있습니다.
How This Grammar Works
I can이라고만 말할 수는 없죠.I eat은 단순한 사실의 진술입니다.I might eat은 아직 Uber Eats 메뉴를 확인 중인 것처럼 들리죠. I must eat은 긴 헬스장 세션 후에 굶어 죽기 직전인 것처럼 들립니다. 이 동사들은 자신만의 규칙을 따릅니다.play나 eat 같은 '일반적인' 동사처럼 행동하지 않죠. 조동사는 반항아입니다. 주요 동사 앞에 to라는 단어를 쓰지 않습니다.I can to swim이라고는 절대 말하지 마세요. 듣는 사람에게 큰 경고 신호가 될 거예요. 또한 -ing 형태도 없습니다.
Formation Pattern
I, you, we, 또는 my cat도 가능합니다.
can, could, may, might, shall, should, will, would, must 중에서 선택하세요.
-s, -ed, -ing를 붙이지 않습니다.
She can speak English.
she임에도 불구하고 can에 -s가 붙지 않았다는 점에 주목하세요.
speak 앞에 to가 없다는 점에 주목하세요.
not을 추가하기만 하면 됩니다.
I cannot (can't) go.
You should not (shouldn't) do that.
Can you help me?
do, does, did를 절대 사용하지 마세요.
Do you can help?
Can you help?
do 가족의 도움이 필요하지 않습니다. 문법계의 독립적인 인플루언서인 셈이죠.
When To Use It
- 일반적인 능력에는
can을 사용합니다.I
cancode. - 허가에는
can이나may를 사용합니다.CanI use your charger? - 강력한 의무에는
must를 사용합니다.You
mustwear a seatbelt. - 조언을 줄 때는
should를 사용합니다.You
shouldwatch that new Netflix show. - 가능성에는
might나could를 사용합니다.It
mightrain later. - 현대적인 텍스트 메시지에서는
can이 거의 모든 상황에 쓰입니다. 하지만may나could를 사용하면 훨씬 더 전문적으로 들립니다. 교수님께 이메일을 보낸다고 상상해보세요.Can I ask a question?도 괜찮지만,Could I ask a question?은 실제로 예습을 한 것처럼 들립니다. 온라인 게임 중이라면 팀원에게 조언하기 위해We
라고 말할 수 있겠죠. 여행 브이로그를 찍고 있다면 흥분을 표현하기 위해shouldrush B!You
라고 말할 수도 있습니다. 각 조동사는 RPG 게임의 캐릭터처럼 특정 역할이 있습니다.mustvisit this café!
Common Mistakes
- 조동사 뒤에
to붙이기. 이것이 1순위 실수입니다. 절대I must to study라고 말하지 마세요. - 3인칭 단수에
-s붙이기.He cans는 틀렸습니다. 항상He can입니다. - 의문문에
do사용하기.Does he can?이라고 하면 사람들이 고개를 갸우뚱할 거예요. - 두 개의 조동사를 함께 사용하려고 하기.
I will can go는 큰 실수입니다. 대신I will be able to go를 사용하세요. must가 매우 강하다는 것을 잊기. 조언에 사용하면 너무 강압적으로 들릴 수 있습니다.- 정중한 요청에서
can과could혼동하기. 모르는 사람에게는could가 항상 더 안전합니다. - «~할 필요가 없다»라고 말하고 싶을 때
mustn't사용하기.mustn't는 '금지'를 뜻합니다.
Contrast With Similar Patterns
MustvsHave to:Must는 개인적인 감정,Have to는 외부 규칙인 경우가 많습니다.ShouldvsOught to: 같은 의미입니다.Should가 훨씬 더 흔하게 쓰입니다.CanvsBe able to:Can은 현재,Be able to는 미래나 과거에 사용합니다.MayvsMight:May가Might보다 일어날 가능성이 약간 더 높습니다.
Quick FAQ
조동사는 항상 똑같나요? A: 네, 절대 형태가 변하지 않습니다.
과거 일에 can을 쓸 수 있나요? A: 아니요, 과거 능력에는 could를 쓰세요.
should가 must보다 강한가요? A: 아니요, must는 명령이고 should는 제안입니다.
ought to에 to가 필요한가요? A: 네, ought to만 to를 사용합니다.
이걸 어떻게 다 기억하나요? A: 기분 전환기(mood-shifters)라고 생각하세요. 문장의 에너지를 바꾸는 장치입니다.
Modal Verb Conjugation (No Change!)
| Subject | Modal | Base Verb | Notes |
|---|---|---|---|
|
I
|
can / should / must
|
work
|
No 'to'
|
|
You
|
can / should / must
|
work
|
Standard form
|
|
He / She / It
|
can / should / must
|
work
|
NO '-s' added
|
|
We
|
can / should / must
|
work
|
Standard form
|
|
They
|
can / should / must
|
work
|
Standard form
|
Common Contractions
| Full Form | Contraction | Usage |
|---|---|---|
|
cannot
|
can't
|
Very common in speech
|
|
should not
|
shouldn't
|
Common for advice
|
|
must not
|
mustn't
|
Used for prohibitions
|
|
shall not
|
shan't
|
Very rare/British
|
Meanings
Modal verbs are a special category of auxiliary verbs used to express ability, possibility, permission, advice, or necessity. They function as 'mood setters' for the main verb that follows them.
Ability & Permission (Can)
Used to express physical or mental ability, or to ask for/give permission in informal settings.
“I can run a marathon in under four hours.”
“Can I borrow your pen for a second?”
Advice & Recommendation (Should)
Used to give suggestions, advice, or to talk about what is ideal or expected.
“You should try the pasta; it's delicious here.”
“We should leave now if we want to catch the train.”
Strong Obligation (Must)
Used to express a firm necessity, a rule, or a personal strong feeling that something is required.
“All passengers must wear a seatbelt.”
“I must remember to call my mother tonight.”
Logical Deduction (Must)
Used when you are almost 100% sure that something is true based on evidence.
“You've been working all day; you must be exhausted.”
“The lights are off; they must be asleep.”
Reference Table
| 조동사 | 의미 | 긍정문 예시 | 부정문 예시 |
|---|---|---|---|
|
can
|
능력 / 허락 / 가능성
|
I `can` speak French.
|
I `can't` speak French.
|
|
should
|
조언 / 추천 / 예상
|
You `should` rest.
|
You `shouldn't` worry.
|
|
must
|
강한 의무 / 필요 / 추측
|
We `must` leave now.
|
You `must not` smoke here.
|
|
could
|
과거 능력 / 공손한 요청
|
I `could` sing well then.
|
`Could` you open the door?
|
|
have to
|
외부적 의무 / 필요
|
I `have to` work late.
|
I `don't have to` go.
|
|
mustn't
|
금지
|
You `mustn't` touch that.
|
|
격식 수준 스펙트럼
May I please have some water? (Restaurant/Home)
Can I have some water, please? (Restaurant/Home)
Can I get a water? (Restaurant/Home)
Gimme a water, yeah? (Restaurant/Home)
조동사: Can, Should, Must
Can
- 능력 I can sing.
- 허락 You can leave.
- 가능성 It can be cold.
Should
- 조언 You should rest.
- 추천 We should go.
- 예상 They should arrive.
Must
- 의무 You must study.
- 필요 We must hurry.
- 추측 He must be tired.
'Must Not' vs. 'Don't Have To' 비교
올바른 조동사 선택하기 (Can, Should, Must)
능력이나 허락에 관한 건가요?
조언이나 추천인가요?
강한 의무나 논리적인 확실성인가요?
조동사 파워업!
능력 표현하기
- • I can run fast.
- • She can solve this problem.
조언하기
- • You should eat healthy.
- • He should apologize.
의무 진술하기
- • We must follow rules.
- • Students must study.
공손한 요청
- • Can you help me?
- • Could you close the door?
수준별 예문
I can play the guitar.
Can you help me?
She can speak English.
We can't come to the party.
You should eat more vegetables.
I must finish my homework.
Should we go to the park?
You mustn't touch that; it's hot!
You should try to arrive ten minutes early.
He must be the new manager; he's wearing a suit.
You don't have to pay now; you can pay later.
Can I suggest a different approach?
The government should have acted much sooner.
There must have been a misunderstanding at the front desk.
You can't have seen Mark; he's in Australia!
Must you make so much noise while I'm working?
One should always consider the ethical implications of such research.
The results can be interpreted in several different ways.
It must be noted that this study has several limitations.
Should you require further assistance, do not hesitate to contact us.
The sheer audacity of the claim must surely give us pause.
One cannot but admire her dedication to the cause.
The policy should, in theory, alleviate the housing crisis.
That he should have failed after such effort is a tragedy.
혼동하기 쉬운
Learners often think 'mustn't' is the negative of 'must' in terms of necessity, but it actually changes the meaning to prohibition.
Both are used for permission, but 'can' is informal and 'may' is formal. Teachers often correct 'Can I...?' with 'I don't know, can you?' to emphasize ability.
They mean the same thing, but 'ought to' is much less common and requires 'to'.
자주 하는 실수
I can to swim.
I can swim.
He cans speak English.
He can speak English.
I no can go.
I can't go.
Do you can help?
Can you help?
You should to rest.
You should rest.
Must you to go?
Must you go?
She shoulds study.
She should study.
You mustn't pay; it's free.
You don't have to pay; it's free.
I musted work yesterday.
I had to work yesterday.
It should be rain tomorrow.
It should rain tomorrow.
I can't help but to wonder.
I can't help but wonder.
He must has forgotten.
He must have forgotten.
Should I'll see him, I'll tell him.
Should I see him, I'll tell him.
문장 패턴
I can ___ but I can't ___.
If you are tired, you should ___.
To be a good student, you must ___.
He isn't answering his phone; he must be ___.
You shouldn't have ___ without ___.
Real World Usage
I can work under pressure and I should be able to start next month.
Can u come tonight? You should definitely be there!
Passengers must present their boarding pass.
You should take this medicine twice a day.
You MUST try this new brunch spot! 😍
Can I get the burger without onions?
We should schedule a meeting to discuss the budget.
The battery must be charged for 4 hours before use.
조동사 + 동사원형 = 마법!
I can swim처럼요. "Always remember this golden rule: modal verbs are *always* followed by the base form of another verb. No 'to', no '-s', no '-ing'!"'Mustn't'와 'Don't Have To' 구분하기
don't have to means 'it's not necessary' (you can choose not to)."'Could'로 더 공손하게 말하기
Can I ask a question?대신
Could I ask a question?이라고 하면 훨씬 부드럽고 정중하게 들린답니다.
While can asks for permission directly, could adds a touch of extra politeness.
영국식 영어 vs. 미국식 영어 'Must'
In British English, must for obligation is often a bit more common than have to in certain contexts.조동사는 변하지 않아요
I can, she can, they can처럼 항상 똑같답니다! "One less thing to worry about! Unlike regular verbs, modal verbs like 'can', 'should', and 'must' don't change their form based on the subject."Smart Tips
Stop! Imagine the modal verb is a 'to-eater'. It eats the 'to' before it can reach the main verb.
Use 'might want to' or 'should perhaps' instead of just 'should' to sound more professional.
It's probably a logical guess, not an obligation. 'It must be raining' doesn't mean the rain is following a rule!
Avoid contractions like 'can't' or 'shouldn't'. Use the full forms 'cannot' and 'should not'.
발음
The Silent 'L'
In 'should', the 'l' is completely silent. It sounds like 'shood'.
Can vs. Can't
In American English, 'can' is often reduced to 'kun', while 'can't' has a clear 'a' sound and a sharp 't' (or a glottal stop).
Mustn't
The first 't' in 'mustn't' is silent. It sounds like 'muss-unt'.
Polite Requests
Can you ↗ help me?
Rising intonation at the end makes the request sound more polite.
Strong Advice
You ↘ SHOULD go.
Stress on the modal verb 'should' emphasizes the importance of the advice.
암기하기
기억법
Modals are 'Bare' and 'Fixed': they use the Bare infinitive and their form is Fixed (no -s).
시각적 연상
Imagine a 'Modal Shield' around the main verb. The shield blocks the 'to' and the 's' from ever touching the verb.
Rhyme
With can, should, and must, the 'to' you must bust; no 's' at the end, they're a learner's best friend.
Story
A king (Must) gives orders, a wise advisor (Should) gives suggestions, and a skilled knight (Can) shows what he is able to do. They all live in a castle where the word 'to' is forbidden.
Word Web
챌린지
Write three sentences about your job or hobby: one thing you CAN do, one thing you SHOULD do better, and one thing you MUST do every day.
문화 노트
British speakers often use 'should' in places where Americans might use 'would' or 'must', especially to sound more polite or indirect.
Americans rarely use 'mustn't' in casual speech, preferring 'can't' or 'not allowed to'. 'Mustn't' can sound very formal or old-fashioned.
Using 'should' instead of 'must' in a business meeting is a common 'hedging' strategy to avoid sounding too bossy to colleagues.
Modal verbs come from Old English 'pre-present' verbs, which were originally past tense forms that took on a present tense meaning.
대화 시작하기
What is one skill you can do really well?
What should a tourist see in your hometown?
What are some things you must do before you turn 30?
If you could change one law in your country, what should it be?
What must have happened for the world to end up in its current state?
일기 주제
자주 하는 실수
Test Yourself
She ___ speak three languages fluently.
Find and fix the mistake:
You shouldn't to worry about the exam.
Choose the correct sentence:
Translate into English: 'No debes usar tu teléfono durante el examen.'
Answer starts with: ["Y...
Score: /4
연습 문제
8 exercisesYou ___ see the new Batman movie; it's great!
She can ___ (speak) three languages fluently.
Find and fix the mistake:
He musts finish his report by tomorrow.
I should call him. -> ___
1. Can, 2. Should, 3. Must
A: Is that the doorbell? B: Yes, it ___ be the pizza delivery guy.
Select the right one:
The past tense of 'must' is 'musted'.
Score: /8
Practice Bank
11 exercisesThey ___ finish their project by Friday.
He can to swim very well.
Choose the correct sentence:
Translate into English: 'Debes estudiar para el examen.'
Arrange these words into a sentence:
Match the modals with their primary function:
We ___ respect other cultures when traveling.
She must to be tired after that long flight.
Choose the correct sentence:
Translate into English: '¿Puedes ayudarme con mi tarea?'
Arrange these words into a sentence:
Score: /11
자주 묻는 질문 (8)
Yes, in informal situations. For example, `Can I use your phone?` is perfectly fine with friends. In formal settings, use `May I...` instead.
They mean the same thing. `Cannot` is the formal, written version, and `can't` is the everyday spoken version. Note that `cannot` is always one word.
Yes, much stronger. `Should` is a suggestion (you have a choice), while `must` is an obligation (you have no choice).
No. Modals cannot be used together. To express future ability, use `I will be able to`.
This is a common mistake made by native speakers because `should've` sounds like `should of`. It is always grammatically incorrect to write `should of`.
Use it for things that are strictly forbidden, like `You mustn't park here`. It is more common in British English than American English.
Yes! You can say `He should be here soon` if you expect him to arrive based on a schedule.
No. There is no such word as `canning`, `shoulding`, or `musting` in English grammar.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
poder / deber / tener que
Spanish modals are followed by an infinitive (with no 'to' equivalent), but they conjugate fully unlike English modals.
pouvoir / devoir
French uses the conditional tense of 'devoir' (devrais) to express 'should', whereas English has a dedicated word.
können / sollen / müssen
German modals still conjugate for person (ich kann, du kannst), while English ones are fixed.
~reru / ~nakereba naranai
Obligation in Japanese is often expressed as a double negative ('if you don't do it, it won't become').
yumkin / yajib
The 'modal' part doesn't change, but the following verb must conjugate for the subject.
néng (能) / yīnggāi (应该) / bìxū (必须)
Chinese doesn't have the 'no-to' or 'no-s' problem because Chinese verbs never change form anyway.
Learning Path
Prerequisites
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[야나두] 조동사 must, have to, should, would, can, could, may, might, will, shall 총정리! (영어회화 필수)
야나두
[시원스쿨] 조동사 can, could, may, might, must, have to, should, would 총정리!
시원스쿨
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### 개요 습관과 일상을 나타낼 때 사용되는 '영문법의 제로 컨디셔널(Zero Conditional)'은, 특정 조건이 반복적으로 충족될...
Can: 능력 표현하기 (Can)
Overview 백플립 할 수 있어? 아니면 그냥 괜찮은 사워도우 빵이라도 구울 수 있니? 어느 쪽이든, 넌 `can`을 사용하고 있는 거...
혼합 가정법: 과거의 행동, 현재의 결과 (Type 2)
### Overview Mixed Conditionals(혼합 조건문), 그중에서도 '과거의 행동이 현재의 결과에 영향을 미치는 경우(Type 2 Mixed C...
Suppose & Supposing: '만약 ~라면' 게임
### Overview 영어 학습이 B2 레벨, 즉 중상급 단계에 도달하면 단순히 의사를 전달하는 수준을 넘어, 상대방의 생각을 자극하...
