Modals of Deduction

Use must, might, may, could and can't to guess how sure we are about something in the present: She must be tired. He might be at home. It can't be true.

These modals express logical conclusions based on evidence, not facts. Must + base verb shows strong certainty that something is true: The lights are off — they must be asleep. Can't + base verb shows strong certainty that something is NOT true (the opposite of must): He can't be at work — it's Sunday. Might/may/could + base verb show possibility — we are not sure: She might know the answer. He could be in the kitchen. For actions happening right now, use must/might/could/can't + be + V-ing: They must be watching TV — I can hear the sound.

+ Subject + must/might/may/could + be (+ V-ing)

• She must be the new teacher.
• He might be stuck in traffic.
• They could be on holiday.

− Subject + can't / might not / may not + be (+ V-ing)

• He can't be serious.
• She might not be at home right now.

? Deductive modals are rarely used in questions; usually: What do you think + clause?

• Do you think he could be lying?
• What do you think is wrong with the car?

• ENThe lights are on, so someone must be home.

  KZЖарық жанып тұр, демек біреу үйде болуы керек.

  RUСвет горит, значит, кто-то должен быть дома.

• ENHe hasn't eaten all day — he must be hungry.

  KZОл күні бойы тамақ ішкен жоқ — ол ашыққан болуы керек.

  RUОн весь день не ел — он, должно быть, голоден.

• ENShe can't be at work; it's a public holiday today.

  KZОл жұмыста бола алмайды; бүгін мереке күні.

  RUОна не может быть на работе; сегодня праздничный день.

• ENThis can't be the right address — the house is empty.

  KZБұл дұрыс мекенжай бола алмайды — үй бос тұр.

  RUЭто не может быть правильный адрес — дом пуст.

• ENHe might be at the gym; he usually trains on Tuesdays.

  KZОл спортзалда болуы мүмкін; ол әдетте сейсенбіде жаттығады.

  RUОн, возможно, в спортзале; он обычно тренируется по вторникам.

• ENThey may be stuck in traffic; the roads are very busy.

  KZОлар кептелісте қалуы мүмкін; жолдар өте тығыз.

  RUОни, возможно, застряли в пробке; дороги очень загружены.

• ENShe could be telling the truth — we have no proof otherwise.

  KZОл шындықты айтып жатқан болуы мүмкін — бізде басқа дәлел жоқ.

  RUОна, возможно, говорит правду — у нас нет других доказательств.

• ENListen — they must be arguing again.

  KZТыңдашы — олар тағы да дауласып жатқан болуы керек.

  RUСлушай — они, должно быть, снова спорят.

• ENHe isn't answering his phone; he might be sleeping.

  KZОл телефонға жауап бермей жатыр; ол ұйықтап жатқан болуы мүмкін.

  RUОн не отвечает на телефон; он, возможно, спит.

• ENThat can't be John — John is on holiday in Spain.

  KZБұл Джон бола алмайды — Джон Испанияда демалыста.

  RUЭто не может быть Джон — Джон в отпуске в Испании.

• ✗ He must to be tired.

  ✓ He must be tired.

  Must is followed directly by the base verb, no 'to'.

• ✗ She mustn't be at home — the lights are off.

  ✓ She can't be at home — the lights are off.

  Use can't, not mustn't, for a logical negative conclusion.

• ✗ He might being in the garden.

  ✓ He might be in the garden.

  Use base verb 'be', not 'being', after modals.

• ✗ They must watching a film now.

  ✓ They must be watching a film now.

  Continuous deduction needs 'be' before V-ing.

Must vs Can't vs Might/May/Could

Must shows you are almost certain something is true. Can't shows you are almost certain something is false. Might/may/could show you are not sure either way.

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