B1 · 중급 챕터 31

Possibility and Probability

5 총 규칙
51 예문
6 분
이 챕터의 규칙 빠른 연습

Chapter in 30 Seconds

Master the art of expressing uncertainty and logical deductions with professional precision.

  • Differentiate between weak and strong possibilities using modal verbs.
  • Make logical deductions based on evidence using 'must' and 'can't'.
  • Use advanced probability adjectives and adverbs to sound more natural.
Stop guessing, start expressing levels of certainty.

배울 내용

Ever wonder how likely something is? This chapter helps you confidently discuss possibilities with may and might, and make logical deductions using must, so you can express yourself more precisely and naturally.

Learning Objectives

By the end of this chapter, you will be able to:

  1. 1
    By the end you will be able to: describe a 30-50% chance of an event happening using may or might.
  2. 2
    By the end you will be able to: conclude that something is definitely true or false based on evidence.
  3. 3
    By the end you will be able to: rank different outcomes from 'unlikely' to 'bound to' using non-modal structures.

챕터 가이드

Overview

As a B1 English learner, you're moving beyond basic communication and starting to express more nuanced ideas. This is where understanding English possibility and probability becomes incredibly useful! Imagine you're making plans, discussing news, or even just wondering about the weather – knowing how to express how likely something is can really boost your confidence and make your English sound much more natural.
This chapter will equip you with essential tools to talk about uncertainty and make logical deductions.
We'll explore how to use modal verbs like may and might to express things that are simply possible, and how must helps you sound confident about a logical conclusion. You'll also learn handy phrases like may well and might well to express a higher degree of probability. By mastering these concepts, you'll be able to discuss potential outcomes, explain why you think something is true, and even confidently state when something just can't be!
These are all key skills for navigating a wide range of everyday conversations at the B1 English grammar level.
Being able to differentiate between something that *might* happen and something that *must* be true based on evidence will help you communicate more precisely. It's about adding depth to your English, allowing you to share your thoughts and reasoning in a clear and convincing way. Get ready to discuss possibilities and probabilities like a pro!

How This Grammar Works

Let's break down the core grammar rules for expressing possibility and probability in English. We use modal verbs to do this, and they always precede a base verb (the infinitive without 'to').
When you're talking about something that is possible, but not certain, you'll use may or might. They are largely interchangeable for present or future possibility. For example,
It may rain later
means there's a chance of rain.
Similarly,
She might be at the library
suggests it's a possibility, but you're not sure. These express general uncertainty or a 'maybe' situation.
Now, if you're quite sure about something based on evidence or logic, you use must. This isn't about obligation; it's about making a logical deduction. If your friend has been studying all night, you could say,
She must be tired.
You're almost certain based on the clues.
This is called the epistemic must. The evidence makes it highly probable.
To add a bit more strength to your predictions, you can use may well or might well. These phrases indicate that something is quite likely because it makes good sense or there are strong reasons for it. For instance, "If he doesn't study, he may well fail the exam" implies that it's a very probable outcome given his actions.
It's stronger than just may or might alone, suggesting a reasonable expectation.
Finally, when you're absolutely certain that something is logically impossible, you use can't. For example, if you see someone enter a room and then immediately leave through the same door, you could say, "She can't be in the room anymore." The evidence tells you it's impossible. It's the opposite of must for logical deduction.
These structures build on each other, allowing you to express varying degrees of certainty.

Common Mistakes

  1. 1✗ Using 'must' for permission instead of logical deduction in this context.
✓ He must be home, his car is in the driveway. (Correct: Logical deduction)
✗ You must go to the party. (Incorrect for probability; this is obligation. For possibility, you might say
You might go to the party if you want.
)
*Explanation:* Remember that the 'must' we're focusing on here is for making a logical guess, not for giving orders or saying something is required.
  1. 1✗ Confusing 'may' and 'might' for past possibility.
✓ She may have forgotten her keys. (Correct for past possibility)
✗ She might forget her keys yesterday. (Incorrect: 'Might' for past possibility needs 'have' + past participle)
*Explanation:* For past possibility or probability, you need to use may have + past participle or might have + past participle. The chapter focuses on present/future, but this is a common extension.
  1. 1✗ Using 'cannot' instead of 'can't' for logical impossibility in informal contexts.
✓ That can't be true! (Correct: Common and natural)
✗ That cannot be true! (Less natural in everyday, conversational English for this specific meaning, though grammatically correct)
*Explanation:* While 'cannot' is grammatically fine, 'can't' is much more common and natural when expressing logical impossibility in conversational English.

Real Conversations

A

A

The lights are off in John's office. He usually works late.
B

B

He must have left already. It's almost 7 PM.
A

A

Do you think Sarah will come to the party?
B

B

She said she was busy, so she might not make it. But she may well surprise us if her meeting finishes early.
A

A

I can hear music from next door.
B

B

Oh, that can't be my neighbour. He's on holiday in Spain this week!

Quick FAQ

Q

Can I use 'may' and 'might' interchangeably for possibility?

Yes, in most cases for present and future possibility, may and might are interchangeable. Some people feel 'might' expresses a slightly weaker possibility, but the difference is very subtle and often not significant in everyday conversation.

Q

How is 'must' for possibility different from 'must' for obligation?

Must for possibility (epistemic) means

I am almost certain based on evidence
(e.g.,
He must be rich; he drives a fancy car.
). Must for obligation means
It is necessary or required
(e.g.,
You must finish your homework.
). The context makes the meaning clear.

Q

Is 'may well' much stronger than 'may'?

Yes, may well expresses a higher degree of probability than just may. It suggests that something is quite likely because there's a logical reason or expectation for it to happen. It's like saying "it's very likely or it's probable."

Q

When should I use 'can't' instead of 'won't be able to' for impossibility?

Use can't when you're making a logical deduction that something is impossible based on facts or evidence ("That can't be true, I saw it myself!"). Use 'won't be able to' for future inability or lack of opportunity ("I won't be able to come tomorrow, I have an appointment.").

Cultural Context

Native English speakers use these modal verbs constantly to soften statements, express uncertainty, and convey different levels of conviction. In casual conversation, you'll hear might and can't a lot, as they add a natural flow. Must for deduction is also very common.
While may well and might well are perfectly natural, they tend to be slightly more formal or used when explaining a reasoned prediction. There aren't significant regional differences in the core usage of these modals, but the frequency of their use may vary slightly between individuals.

주요 예문 (8)

1

I `may go` to the gym after work, if I'm not too tired.

퇴근하고 너무 피곤하지 않으면 헬스장에 갈 수도 있어요.

영어의 가능성: May와 Might
2

They `might be` stuck in traffic, which is why they're late.

그들이 차가 막혀서 늦을 수도 있어요.

영어의 가능성: May와 Might
3

Look at all the snow! It `must be` freezing outside.

눈이 이렇게 많이 오다니! 밖은 엄청 추울 거야.

'Must'를 이용한 논리적 추측 (인식적)
4

He's wearing a doctor's coat. He `must be` a doctor.

그는 의사 가운을 입고 있어요. 의사임이 틀림없어요.

'Must'를 이용한 논리적 추측 (인식적)
5

She **may well pass** the exam; she studied all week.

그녀는 시험에 합격할 가능성이 아주 높아요. 일주일 내내 공부했거든요.

확률 부스터: May Well & Might Well
6

The package **might well arrive** tomorrow, as it shipped yesterday.

어제 배송되었으니, 소포는 내일 도착할 가능성이 아주 높아요.

확률 부스터: May Well & Might Well
7

That pizza place `can't be closed` already, it's only 8 PM!

그 피자집이 벌써 문 닫았을 리 없어, 겨우 저녁 8시인데!

논리적 불가능성 (그럴 리 없어!)
8

My internet `couldn't have gone out`. I just paid the bill yesterday.

우리 집 인터넷이 끊겼을 리 없어. 어제 막 요금 냈거든.

논리적 불가능성 (그럴 리 없어!)

팁과 요령 (4)

💡

정중한 제안에 사용하기

친구에게 조언을 부드럽게 하고 싶을 때 might를 써보세요. «이렇게 해!» 대신 «이걸 고려해 보는 게 어때?» 하고 말하는 것처럼요:
You might want to consider this.
frontend.learn_grammar.from_rule: 영어의 가능성: May와 Might
💡

증거를 찾아보세요!

'must'로 추측하기 전에, 확실한 증거가 있는지 꼭 확인해야 해요. 증거가 강할수록 'must'를 더 자신 있게 쓸 수 있어요.
He must be exhausted.
frontend.learn_grammar.from_rule: 'Must'를 이용한 논리적 추측 (인식적)
💡

예측에 힘을 실어주세요

친구가 '내일 비 올까?' 물어볼 때, 그냥 'It may rain.' 대신 '구름이 잔뜩 꼈으니 비 올 것 같아'처럼 근거 있는 예측을 할 때 사용하면 좋아요.
It may well rain tomorrow.
처럼요.
frontend.learn_grammar.from_rule: 확률 부스터: May Well & Might Well
💡

반대를 생각해 봐요!

'must be'가 '확실히 ~일 것이다'라는 강한 긍정적 추측일 때 ('He must be rich'), 'can't be'는 그 반대인 '확실히 ~가 아닐 것이다'라는 논리적인 부정 추측이에요 ('He can't be poor'). 이렇게 생각하면 논리적 연결을 더 잘 이해할 수 있을 거예요.
frontend.learn_grammar.from_rule: 논리적 불가능성 (그럴 리 없어!)

핵심 어휘 (6)

Evidence facts or signs that show something is true Likelihood the chance that something will happen Certain completely sure about something Possible able to be done or happen Impossible not able to occur or exist Predict to say what will happen in the future

Real-World Preview

coffee

Solving an Office Mystery

Review Summary

  • Subject + may/might + base verb
  • Subject + must + base verb
  • Subject + can't + base verb

자주 하는 실수

In English, we do not use 'must not' for logical deductions. We use 'can't' to say something is logically impossible.

Wrong: It must be not true.
정답: It can't be true.

Modal verbs like 'might' never take an 's' in the third person singular.

Wrong: He mights come to the party.
정답: He might come to the party.

Adverbs of probability like 'probably' usually go after the first auxiliary verb or before the main verb.

Wrong: Probably I will see you later.
정답: I will probably see you later.

Next Steps

You've unlocked a new level of English! Being able to speculate and deduce makes your conversations much more interesting. Keep practicing those 'must be' moments!

Look out the window and make 5 'must be' and 5 'might be' observations about people you see.

Continue to: Collocations and Word Partnerships

빠른 연습 (10)

올바른 형태를 고르세요

She's always late, so she ___ miss the bus.

✓ Correct! ✗ Not quite. Correct answer: may well
May well은 그녀가 항상 늦는 습관을 바탕으로 버스를 놓칠 가능성이 높다는 것을 나타내요. May as well은 제안할 때, well may는 잘못된 어순이에요.

frontend.learn_grammar.from_rule: 확률 부스터: May Well & Might Well

문장에서 실수를 찾아 고치세요.

Find and fix the mistake:

They might to forget about our meeting.

✓ Correct! ✗ Not quite. Correct answer: They might forget about our meeting.
might와 같은 조동사 뒤에는 to 없이 주동사의 동사원형(forget)이 바로 옵니다.

frontend.learn_grammar.from_rule: 영어의 가능성: May와 Might

실수를 찾아 고치세요

Find and fix the mistake:

If you don't save, you might as well run out of money.

✓ Correct! ✗ Not quite. Correct answer: If you don't save, you might well run out of money.
Might well은 저축하지 않았을 때 돈이 바닥날 가능성이 높다는 논리적인 결과를 나타내요. Might as well은 제안을 의미해요.

frontend.learn_grammar.from_rule: 확률 부스터: May Well & Might Well

논리적 추측을 완성하기 위해 올바른 형태를 선택하세요.

The lights are off and the door is locked. She ___ asleep.

✓ Correct! ✗ Not quite. Correct answer: must be
현재 논리적 추측에는 'must' 뒤에 동사 'to be'의 원형을 사용해요.

frontend.learn_grammar.from_rule: 'Must'를 이용한 논리적 추측 (인식적)

Fill in the blank.

It is ___ to rain.

✓ Correct! ✗ Not quite. Correct answer: likely
Likely takes 'to'.

frontend.learn_grammar.from_rule: Probability: Likely, Unlikely, Bound To, Definitely, Probably

문장에서 틀린 부분을 찾아 고치세요.

Find and fix the mistake:

They mustn't be home. Their car isn't in the driveway.

✓ Correct! ✗ Not quite. Correct answer: They can't be home. Their car isn't in the driveway.
여기서 'Mustn't be'는 틀렸습니다. 화자는 증거(차가 없는 것)에 근거하여 논리적인 추론을 하고 있으므로, 논리적 불가능성을 표현하기 위해 'can't be'가 적절한 선택입니다.

frontend.learn_grammar.from_rule: 논리적 불가능성 (그럴 리 없어!)

논리적 불가능성을 표현하는 올바른 형태를 고르세요.

He's only 16, so he ___ a licensed driver yet.

✓ Correct! ✗ Not quite. Correct answer: can't be
16세이므로 (대부분의 지역에서) 면허를 가진 운전자가 되는 것은 논리적으로 불가능합니다. 'Can't be'는 이러한 불가능성을 표현합니다.

frontend.learn_grammar.from_rule: 논리적 불가능성 (그럴 리 없어!)

`may`나 `might`를 올바르게 사용한 문장을 고르세요.

Choose the correct sentence:

✓ Correct! ✗ Not quite. Correct answer: He may not understand the instructions.
May not 뒤에는 동사원형(understand)이 올바르게 사용되었습니다. 다른 선택지들은 동사 형태가 틀렸습니다.

frontend.learn_grammar.from_rule: 영어의 가능성: May와 Might

Choose the correct sentence.

Which is correct?

✓ Correct! ✗ Not quite. Correct answer: I will probably go.
Probably before verb.

frontend.learn_grammar.from_rule: Probability: Likely, Unlikely, Bound To, Definitely, Probably

문장을 완성하기 위해 올바른 형태를 고르세요.

She ___ be at the library right now, I'm not sure.

✓ Correct! ✗ Not quite. Correct answer: may
May는 조동사이며 형태가 변하지 않습니다. 그 뒤에는 동사원형(be)이 옵니다.

frontend.learn_grammar.from_rule: 영어의 가능성: May와 Might

Score: /10

자주 묻는 질문 (6)

핵심 아이디어는 어떤 일이 가능하거나 일어날 법하지만, 100% 확실하지는 않다는 것을 표현하는 거예요.
It may rain later
(나중에 비가 올 수도 있어)나
She might be busy
(그녀는 바쁠 수도 있어)처럼, 확실한 진술을 하지 않고 추측하거나 짐작할 수 있게 해줘요.
가능성을 표현하는 대부분의 현대적인 맥락에서는 네, 거의 바꿔 쓸 수 있어요. might가 가끔은 약간 더 낮은 확률을 암시할 수도 있지만, 그 차이는 매우 미묘하고 일상 대화에서는 일관되게 관찰되지 않아요.
가지고 있는 증거를 바탕으로 강하고 확신에 찬 추론을 하는 것이 핵심이에요. 'X가 있으니 Y가 must be 사실일 거야'라고 말하는 것처럼, 유일한 논리적 결론이라고 생각할 때 사용해요.
매우 확신하는 거예요! 95-99%의 확률이라고 생각하면 돼요. 증거가 너무 강해서 결론이 거의 부정할 수 없을 때 'must'를 사용해요. 예를 들어, '불이 꺼져 있으니 그는 must be 잠들었을 거야'처럼요.
may well은 '아주 그럴 것 같다' 또는 '매우 가능성이 높다'는 뜻이에요. 그냥 may보다 훨씬 더 확실한 가능성을 나타내죠. 논리적인 이유가 있을 때 주로 사용해요.
둘 다 높은 가능성을 나타내서 거의 비슷하게 쓸 수 있어요. might well이 때로는 may well보다 아주 살짝 더 조심스럽거나 가상적인 상황에서 쓰일 때도 있지만, 핵심 의미는 '강한 가능성'으로 같아요.
이전 챕터
The Second Conditional
다음 챕터
Collocations and Word Partnerships
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