Unit 1 Grammar

Obligation:

Must    for strong obligations which express the authority of the speaker or writer.

·         A for formal rules or laws.

·         B for suggestions, advice or recommendations that the speaker or writer feels strongly about.

Have to   for strong obligations which express the authority of a third person, rather than that of the speaker or writer

·         When the speaker wants to show they are not responsible for imposing the obligation, or does not agree with it.

·         When the speaker or writer is reminding someone about a rule or law.

Have got to   is more informal than Have to.

·         For direct commands

·         For emphasis

Need to    to express needs or necessities rather than strict obligations

Negative forms

Musn’t      expresses prohibition – negative rules and laws or strong advice.

Don’t have to / have not got to   -  lack of obligation or necessity

Do not need to / Needn’t   lack of obligation or necessity and are similar in meaning to don’t have to.

Did not need to + infinitive means: “It was not necessary, so we didn’t do it”

Needn’t have + past participle means: “It was not necessary, but we did it in spite of this”

Permission and Prohibition

Can / can’t   commonest way of expressing permission and prohibition.

  May I ..? means the same as Can I…?  but more formal and more polite.

Other expression of permission and prohibition

·         be allowed to + infinitive

·         be permitted to + infinitive

·         let + infinitive without to

Other expressions of prohibition:

You aren’t allowed to …

Smoking is not permitted in…

You are not permitted to smoke…

People are forbidden to smoke…

The workers have been prohibited from …

Nigel has been banned from driving….