Modal verbs: permission, obligation, prohibition, necessity — Explanation

Practice B2 modal verbs with exercises on permission, obligation, prohibition, and necessity. Improve accuracy with clear examples and answers.

Modal Verbs Exercises

Modal Verbs Modal verbs are important in English to express rules, responsibilities and possibilities. B2 level learners are also expected to use modal verbs accurately and flexibly, particularly with regard to permission, obligation, prohibition and necessity. This guide helps you understand how to use them clearly and naturally.

Permission

We use modals for giving and asking permission.

Common Modals:

• can – informal permission
• could – more polite/formal
• may – very formal or official

Examples:

• Can I leave early today?
• Could I use your phone for a moment?
• You may enter the room now.

Tip:
“Can” is the most common in everyday conversation, and “may” is often used in formal situations like rules or announcements.

Obligation

Obligation means something owed; a duty or commitment.

Common Structures:

• must – strong obligation (often personal or formal rules)
• have to – external obligation (rules, laws, situations)
• need to – similar to “have to,” slightly softer

Examples:

• You must wear a seatbelt.
• I have to finish this report by tomorrow.
• We need to study more for the exam.

Difference:

• Must is often used by the speaker (internal or strong authority)
• Have to is used for external rules or circumstances

Prohibition

A prohibition is something that is not allowed.

Common Structures:

• must not (mustn’t) – strong prohibition
• cannot (can’t) – common and less formal

Examples:

• You mustn’t smoke in this area.
• You can’t park here.

Note:
The word “mustn’t” is stronger and is often used in formal rules . “Can’t” is more common in everyday speech.

Necessity (or Lack of Necessity)

Modal verbs are used to express whether something is necessary or not.

Necessity:

• must / have to / need to

Lack of Necessity:

• don’t have to – not necessary
• don’t need to – not necessary

Examples:

• You must submit the form today.
• You don’t have to come if you’re busy.
• We don’t need to buy more food.