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기본 개념BASIC CONCEPT
⭐ TODAY'S KEY GRAMMAR
Modals of Deduction
과거 상황에 대한 확신 또는 부정 추측을 표현하는 구조

must have + p.p. → 분명 ~했을 거야 (강한 확신, 90% 이상)

can't have + p.p. → 절대 ~하지 않았을 거야 (강한 부정, 거의 0%)

논리적 단서나 정황을 바탕으로 과거를 추론합니다.

  • He must have left early. (불이 꺼져 있어)그는 분명 일찍 떠났을 거야.
  • She can't have forgotten. (메모를 했으니까)그녀가 잊었을 리가 없어.
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문법 규칙GRAMMAR RULES
강한 확신 · MUST HAVE
must have + p.p.
He must have left.
강한 부정 · CAN'T HAVE
can't have + p.p.
She can't have forgotten.
과거 추론 · PAST ONLY
시제는 항상 과거
논리적 단서 기반
진술문 위주 · STATEMENTS
의문문에서는 거의 불사용
주로 진술문에서 사용
  • 기본 구조: 주어 + must/can't + have + 과거분사(p.p.)
  • must have + p.p. → 과거에 분명히 일어난 일에 대한 확신
  • can't have + p.p. → 과거에 일어나지 않았을 것이라는 강한 부정
  • 논리적 단서나 정황을 바탕으로 사용
  • 구어체와 글쓰기 모두에서 사용 가능
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긍정문 예시POSITIVE EXAMPLES
  • He must have left early.불이 꺼져 있어 — 분명 일찍 떠났을 거야.
  • She must have studied hard.시험을 잘 봤어 — 분명 열심히 공부했을 거야.
  • They must have arrived by now.길이 막히지 않았어 — 지금쯤 도착했을 거야.
  • You must have been tired.늦게까지 일했잖아 — 분명 피곤했을 거야.
  • He must have forgotten his keys.문 앞에 서 있어 — 열쇠를 잊었나 봐.
  • He can't have forgotten the meeting.캘린더에 적혀 있어 — 잊었을 리가 없어.
  • She can't have gone home.가방이 여기 있어 — 집에 갔을 리가 없어.
  • They can't have finished already.너무 빨라 — 벌써 끝났을 리가 없어.
  • You can't have seen him.그는 해외에 있어 — 그를 봤을 리가 없어.
  • We can't have made that mistake.다시 확인했어 — 그런 실수를 했을 리가 없어.
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의문문 예시QUESTION EXAMPLES
  • Why do we say "must have gone" instead of "must went"?왜 "must went"가 아니라 "must have gone"이라고 하나요?
  • Can you explain "can't have seen him"?"can't have seen him"을 설명해 줄 수 있나요?
  • What does "must have been tired" mean?"must have been tired"는 무슨 뜻인가요?
  • What clues help us use modals of deduction?추론 조동사를 사용하는 데 어떤 단서가 도움이 되나요?
  • What's the difference between "must have" and "might have"?"must have"와 "might have"의 차이는?
  • When do we use "can't have" instead of "didn't"?언제 "didn't" 대신 "can't have"를 사용하나요?
  • How certain are we when using "must have"?"must have"를 사용할 때 얼마나 확신하나요?
  • Can you show the difference between "must be" and "must have been"?"must be"와 "must have been"의 차이를 보여줄 수 있나요?
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상황별 대화 흐름SITUATIONAL DIALOGUES
🏫 학교 상황 · SCHOOL
A: She got full marks again.
B: She must have studied a lot.
A: Definitely, her dedication shows.
✈️ 여행 상황 · TRAVEL
A: They're not at the train station.
B: They must have taken a taxi instead.
A: That makes perfect sense.
💼 직장 상황 · OFFICE
A: He didn't reply to my email.
B: He must have missed it somehow.
A: I'll resend it with high priority.
💻 온라인 상황 · ONLINE
A: She posted that at 3 a.m.
B: She must have stayed up all night.
A: That's dedication to her work.
🏠 가족 상황 · FAMILY
A: Dad's shoes are missing from the entrance.
B: He must have gone for his morning walk.
A: Let's wait for him to come back.
🏥 병원 상황 · HOSPITAL
A: She's not in her hospital room.
B: She can't have left without permission.
A: Let's check with the nurse's station.
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문장 결합 연습SENTENCE COMBINING
I'm sure he left early.
→ He must have left early.
I'm sure she studied hard.
→ She must have studied hard.
I'm sure they arrived.
→ They must have arrived.
I'm sure you were tired.
→ You must have been tired.
It's impossible he forgot.
→ He can't have forgotten.
It's impossible she went home.
→ She can't have gone home.
It's impossible they finished.
→ They can't have finished.
It's impossible you saw him.
→ You can't have seen him.
It's impossible we made that mistake.
→ We can't have made that mistake.
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실생활 사용 예시REAL-LIFE USAGE
  • She must have studied all night.🏫 학교 — 밤새 공부했나 봐.
  • He must have missed the email.💼 직장 — 이메일을 놓쳤나 봐.
  • They must have taken a taxi.✈️ 여행 — 택시를 탔나 봐.
  • He must have gone for a walk.🏠 가족 — 산책 갔나 봐.
  • She can't have left without permission.🏥 병원 — 허락 없이 갔을 리가 없어.
  • They must have had a big sale.🛒 쇼핑 — 큰 세일이 있었나 봐.
  • He can't have forgotten about the party.🎉 파티 — 파티를 잊었을 리가 없어.
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자주 쓰이는 패턴COMMON PATTERNS
강한 확신 · MUST HAVE + P.P.
He must have left early.
단서: 불이 꺼져 있어 → 분명 떠났을 거야
강한 부정 · CAN'T HAVE + P.P.
She can't have forgotten.
단서: 메모를 했어 → 잊었을 리가 없어
상태 추론 · MUST HAVE BEEN
You must have been tired.
단서: 늦게까지 일했어 → 분명 피곤했을 거야
불가능 추론 · CAN'T HAVE BEEN
We can't have been wrong.
단서: 증거가 명확해 → 틀렸을 리가 없어
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흔한 실수COMMON MISTAKES
✗ He must went home.
✓ He must have gone home.
must 뒤에 have + p.p. 구조 필수
✗ She can't forgot.
✓ She can't have forgotten.
can't 뒤에 have + p.p. 구조 필수
✗ They must have arrive.
✓ They must have arrived.
have 뒤에 과거분사(p.p.) 필수
✗ He must been tired.
✓ He must have been tired.
must와 been 사이에 have 필수
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레벨업 팁LEVEL-UP TIPS
TIP 1 · 단서 찾기
추론 조동사를 사용하려면 논리적 단서가 필요합니다. "불이 꺼져 있어" → must have left
TIP 2 · must have vs might have
must have는 90% 이상 확신, might have는 50% 정도 추측입니다.
TIP 3 · 현재 vs 과거
must be = 현재 추론 ("He must be tired"), must have been = 과거 추론 ("He must have been tired")
TIP 4 · 미스터리 풀기
추리 소설이나 뉴스에서 자주 등장합니다. 일상에서도 단서를 보고 추론하는 연습을 해보세요.
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연습문제PRACTICE EXERCISES

빈칸에 must have 또는 can't have를 넣어 문장을 완성하세요.

  • He ___ left early. (불이 꺼져 있어) (must have)
  • She ___ forgotten. (메모를 했어) (can't have)
  • They ___ arrived by now. (must have)
  • You ___ seen him. (그는 해외에 있어) (can't have)
  • She ___ studied hard. (만점이야) (must have)
  • He ___ gone home. (가방이 여기 있어) (can't have)
  • We ___ missed the bus. (정류장에 아무도 없어) (must have)
  • They ___ finished already. (너무 빨라) (can't have)
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자가진단 체크리스트SELF-CHECK
  • must have + p.p.가 강한 확신임을 안다.
  • can't have + p.p.가 강한 부정 추측임을 안다.
  • 논리적 단서를 바탕으로 추론 문장을 만들 수 있다.
  • must be(현재)와 must have been(과거)의 차이를 안다.
  • must have와 might have의 확신도 차이를 안다.
  • 일상 대화에서 추론 표현을 자연스럽게 사용할 수 있다.
  • 흔한 실수 4가지를 이해했다.