Modal Verbs in English: Uses, Structures and Grammar Rules Explained

Modal Verbs in English

Ability and permission: can, could, to be able to, to be allowed to.

Possibility: may, might, could. Deduction: can't, must. No debe y debe (lógico).

Obligation: must, have to. Lack of obligation: needn't (no hace falta), don't have to.

Ought to, should, shouldn't (consejos). Had better + infinitive (más vale que).

Modal Verbs with Perfect Infinitive

• Must have + past participle: certeza lógica sobre el pasado.
• Can't have + past participle: imposible que sucediera en el pasado.
• May / might / could have + past participle: posibilidad en el pasado.
• Could have + past participle: acción que podría haber sucedido, pero no sucedió.
• Should have + past participle: opinar sobre algo que no cambió.
• Shouldn't have + past participle: arrepentimiento o crítica.

Conditionals

Useful linking expressions: if, unless (if not), even if, as long as, providing that (mainly in the first conditional).

Types of Conditionals

• Zero conditional: if/when + present, present or imperative. Used for general truths.
• First conditional: if/unless + present, will + infinitive. Possible situations and warnings.
• Second conditional: if + past simple, would + infinitive. Improbable or hypothetical situations.
• Third conditional: if + past perfect, would have + past participle. Situations that did not happen.

Wishes and Hopes

Wish + past simple / past continuous / could (ojalá, desearía): I wish I were taller.

I hope + present: I hope I pass the exam.

Relative Clauses

The relative pronoun (who / that) can be omitted when it is not the subject of the clause.

Prepositions at the End or Beginning

Informal (preposition at the end): Who did they play for?

Formal (preposition at the beginning): For whom did they play?

Reported Speech and Passive Structures

Structure: It + be + verb in passive reported speech + that → subject + be + verb in passive + infinitive.

It is said that marriage makes men live longer. → Marriage is said to make men live longer. (Se dice que el matrimonio hace que los hombres vivan más.)

Causative Structures

Have something done and get something done (me voy a hacer un piercing, voy a pintar el piso...).

To emphasize that someone does something they would not normally do, use a reflexive pronoun: herself, yourselves, etc.

Verbs Followed by Gerunds or Infinitives

Verb + Gerund

Admit, advise, avoid, can't help, can't stand, can't imagine, can't face, complete, consider, discuss, dislike, don't mind, enjoy, finish, forget, give up, hate, imagine, keep, like, love, mention, mind, miss, practise, recommend, regret, remember, report, resist, risk, start, stop, suggest, try, understand.

(Como sustantivos, detrás de preposiciones y detrás de los verbos anteriores.)

Verb + Infinitive

Afford, agree, appear, arrange, ask, attempt, beg, choose, consent, dare, decide, demand, deserve, expect, fail, forget, hesitate, hope, intend, learn, like, manage, mean, need, offer, prepare, pretend, promise, refuse, remember, seem, threaten, wait, want, wish.

Verbs That Change Meaning

Stop, go, regret, try, remember, like, forget: the gerund refers to an action that happened before or at that moment; the infinitive refers to a future or intended action.