Grammar Exercise: Modals (Mustn’t or Needn’t)

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Grammar Exercise – Modals of prohibition and lack of necessity (mustn’t or needn’t)

Do the exercise below on modals of prohibition and lack of necessity (mustn’t or needn’t) and click the button to check your answers.

(Before doing the exercises, you may want to read the lessons on modals and present and past modals)

Short Recap: Modals of Prohibition and Lack of Necessity

Mustn’t expresses prohibition or what is not allowed:

Example: You mustn’t use your phone during class.

Needn’t conveys lack of necessity, meaning something is not required:

Example: You needn’t bring any snacks; I’ve already prepared some.

Mustn’t or Needn’t Exercise with Answers

Exercise Instructions

Choose the correct modal verb (mustn’t or needn’t) to complete each sentence based on the context. Remember:

Use mustn’t for prohibition (when something is not allowed).
Use needn’t for lack of necessity (when something is not required).

Click the “Check Answer” button after completing the exercise to see your score!

mustn’t vs needn’t exercises

Choose the correct answer (mustn't or needn't)

Nancy Select an option: go to bed early; tomorrow is her day off.
You Select an option: smoke on buses. It's forbidden.
You Select an option: do it now; you can finish it later.
Students Select an option: use their mobile phones during the lessons.
You Select an option: buy any meat. There is plenty of it in the fridge.
You Select an option: bring a swim suit. I can lend you one.
It's a secret. You Select an option: tell anybody.
You Select an option: do the washing up; we have a dishwasher.
You really Select an option: be late again.
You Select an option: drink at all if you plan to drive.

Tags: Exercises on Modals