B1 · Intermediário Capítulo 31

Possibility and Probability

5 Regras totais
51 exemplos
6 min
Regras neste capítulo Prática rápida

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.

O que você vai aprender

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.

Guia do capítulo

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.

Exemplos-chave (8)

1

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

Eu talvez vá à academia depois do trabalho, se não estiver muito cansado.

Possibilidade em Inglês: May e Might
2

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

Eles podem estar presos no trânsito, por isso estão atrasados.

Possibilidade em Inglês: May e Might
3

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

Olha quanta neve! Deve estar congelando lá fora.

Suposição Lógica com 'Must' (Epistêmico)
4

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

Ele está usando um jaleco de médico. Deve ser médico.

Suposição Lógica com 'Must' (Epistêmico)
5

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

É bem provável que ela passe no exame; ela estudou a semana toda.

Potenciador de Probabilidade: May Well & Might Well
6

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

O pacote pode muito bem chegar amanhã, já que foi enviado ontem.

Potenciador de Probabilidade: May Well & Might Well
7

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

Aquela pizzaria não pode estar fechada já, são só 20h!

Impossibilidade Lógica (Não pode ser!)
8

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

Minha internet não poderia ter caído. Eu acabei de pagar a conta ontem.

Impossibilidade Lógica (Não pode ser!)

Dicas e truques (4)

💡

Sugestões educadas

Você quer dar um conselho de um jeito legal, sem parecer mandão? 'Might' é perfeito! Em vez de Faça isso, tente algo como
You might want to consider this
para soar mais colaborativo.
frontend.learn_grammar.from_rule: Possibilidade em Inglês: May e Might
💡

Procure pelas evidências!

Antes de usar 'must' para adivinhação lógica, sempre verifique se você tem provas sólidas. Quanto mais forte a evidência, mais confiante você pode estar com 'must'. Imagine seu amigo que não dorme há 2 dias. Você diria:
He must be exhausted.
frontend.learn_grammar.from_rule: Suposição Lógica com 'Must' (Epistêmico)
💡

Turbine Suas Previsões

O 'may well' e o 'might well' dão mais 'certeza' às suas previsões. Use quando tiver bons motivos para crer em algo, deixando sua fala mais 'informada' e 'elegante'. Por exemplo:
She may well pass the exam; she studied all week.
frontend.learn_grammar.from_rule: Potenciador de Probabilidade: May Well & Might Well
💡

Pense no contrário

Se você usaria must be para uma dedução positiva forte (tipo, 'Ele deve ser rico'), então can't be é o seu oposto lógico negativo (tipo, 'Ele não pode ser pobre'). Isso ajuda a conectar as ideias!
He must be rich
vs "He can't be poor".
frontend.learn_grammar.from_rule: Impossibilidade Lógica (Não pode ser!)

Vocabulário-chave (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

Erros comuns

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.
Correto: 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.
Correto: 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.
Correto: 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

Prática rápida (10)

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

Escolha a forma correta para completar o palpite lógico.

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

✓ Correct! ✗ Not quite. Correct answer: must be
Para um palpite lógico no presente, use 'must' seguido da forma base do verbo 'to be'.

frontend.learn_grammar.from_rule: Suposição Lógica com 'Must' (Epistêmico)

Encontre e corrija o erro

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 well' indica uma forte probabilidade de ficar sem dinheiro como consequência de não poupar, enquanto 'might as well' sugere fazer isso como uma opção.

frontend.learn_grammar.from_rule: Potenciador de Probabilidade: May Well & Might Well

Escolha a forma correta para completar a frase.

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

✓ Correct! ✗ Not quite. Correct answer: may
May é um verbo modal e não muda de forma. Ele é seguido pela forma base do verbo (be).

frontend.learn_grammar.from_rule: Possibilidade em Inglês: May e Might

Escolha a forma correta

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

✓ Correct! ✗ Not quite. Correct answer: may well
'May well' expressa uma forte probabilidade baseada na sua constante demora. 'May as well' é para sugestões, e 'well may' tem a ordem incorreta.

frontend.learn_grammar.from_rule: Potenciador de Probabilidade: May Well & Might Well

Encontre e corrija o erro na frase.

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.
'Mustn't be' está incorreto aqui. O falante está fazendo uma dedução lógica com base em evidências (o carro não está lá), então 'can't be' é a escolha apropriada para expressar impossibilidade lógica.

frontend.learn_grammar.from_rule: Impossibilidade Lógica (Não pode ser!)

Fix the error.

Find and fix the mistake:

He is bound that he wins.

✓ Correct! ✗ Not quite. Correct answer: He is bound to win.
Bound to + infinitive.

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

Escolha a forma correta para expressar impossibilidade lógica.

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

✓ Correct! ✗ Not quite. Correct answer: can't be
Como ele só tem 16 anos, é logicamente impossível que ele seja um motorista licenciado (na maioria dos lugares). 'Can't be' expressa essa impossibilidade.

frontend.learn_grammar.from_rule: Impossibilidade Lógica (Não pode ser!)

Encontre e corrija o erro no palpite lógico negativo.

Find and fix the mistake:

He must not be hungry; he just ate a huge burger.

✓ Correct! ✗ Not quite. Correct answer: He can't be hungry; he just ate a huge burger.
Para palpites lógicos negativos, usamos 'can't' ou 'couldn't', não 'must not'. 'Must not' implica proibição.

frontend.learn_grammar.from_rule: Suposição Lógica com 'Must' (Epistêmico)

Encontre e corrija o erro na frase.

Find and fix the mistake:

They might to forget about our meeting.

✓ Correct! ✗ Not quite. Correct answer: They might forget about our meeting.
Verbos modais (might) são seguidos diretamente pela forma base do verbo principal (forget), sem to.

frontend.learn_grammar.from_rule: Possibilidade em Inglês: May e Might

Score: /10

Perguntas comuns (6)

A ideia principal é mostrar que algo é possível ou provável, mas não totalmente certo. Eles deixam você especular ou adivinhar sem se comprometer com uma afirmação definitiva, tipo:
It may rain later
(Pode chover mais tarde) ou
She might be busy
(Ela pode estar ocupada).
Na maioria dos casos modernos, para expressar possibilidade, sim, eles são bem intercambiáveis. Embora might possa às vezes sugerir uma probabilidade um pouco menor, a diferença é quase imperceptível e não é algo que os falantes nativos se preocupem na fala do dia a dia.
É tudo sobre fazer uma dedução forte e confiante com base nas evidências que você tem. Você está dizendo: 'Dado X, Y must be true' porque é a única conclusão lógica. Pense que seu amigo está com os olhos vermelhos e inchados, você pensa:
She must have been crying.
Bem certo! Pense em 95-99% de probabilidade. Você usa 'must' quando a evidência é tão forte que a conclusão parece quase inegável. Por exemplo, se as luzes estão apagadas na casa do vizinho à meia-noite, você pensa:
The lights are off, so he must be asleep.
'May well' significa que algo é 'muito provável' ou 'altamente provável', com mais certeza do que apenas 'may'. Implica uma razão lógica para essa maior probabilidade. Por exemplo:
It may well rain later.
São bem 'intercambiáveis' para alta probabilidade. 'Might well' pode ser um pouco mais 'cauteloso' ou usado em 'hipóteses', mas o sentido de grande probabilidade é o mesmo. Exemplo:
She might well call later.
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