General English C1 · Lesson 7A

Grammar Bank

The rules behind this lesson — form, use, model sentences and the mistakes to avoid.

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Grammar focus of this lesson

permission, obligation, and necessity

1 structure

Permission, obligation and necessity
Precise modality across present, past and formal registers.
I've got this
Rules & form
- ›Permission: can, may, be allowed / permitted to.
- ›Obligation: must, have to, be required to, be obliged to.
- ›Absence of obligation: needn't, don't have to, not be required to.
- ›Past: had to, was allowed to, needn't have done vs didn't need to do.
- ›Prohibition: mustn't, may not, be prohibited from + -ing.
Examples
- “Contractors are required to complete the induction.”
- “You needn't have flown out — the call would have done.”
- “Staff are prohibited from sharing credentials.”
Watch out · needn't have done = you did it unnecessarily; didn't need to = maybe you never did it.
Your own example