Modal Verbs of Necessity

Exercises

Explanation

The most common modal verbs of necessity level are: must, have to, need to, ought to, and shall (in formal contexts).

1. Must – strong personal obligation

Must is used when the speaker feels something is very important. The obligation often comes from the speaker’s own feelings, beliefs, or sense of responsibility.

Examples:

• I must call my grandmother today; I haven’t spoken to her in weeks.

• You must follow the safety rules during the experiment.

The negative form (must not / mustn’t) shows prohibition—something is not allowed.

Examples:

• You mustn’t touch the museum displays.

• Students mustn’t eat in the computer room.

Important: Must has no past form. For the past, we use had to.

2. Have to – external obligation

Have to describes a necessity that comes from rules, laws, schedules, or other people, not from personal opinion.

Examples:

• I have to finish this report because my manager needs it today.

• All cyclists have to wear a helmet in this area.

Tense changes:

• Present: I have to leave now.

• Past: I had to leave early yesterday.

• Future: I will have to finish the project soon.

“Have got to” – informal alternative

Used mainly in British English and only in the present:

• I’ve got to hurry; the shop closes soon.

3. Need to – practical necessity

Need to expresses a general or practical requirement. It often describes something necessary for success, health, or good results.

Examples:

• You need to back up your files regularly.

• She needs to rest after such a long journey.

Negative form:

• You don’t need to come early. (It’s optional.)

• He doesn’t need to buy a ticket; he already has one.

In British English, we sometimes use needn’t:

• You needn’t bring any snacks; we have enough.

4. Ought to – moral advice or expectation

Ought to gives strong advice, often connected to what is morally right or socially expected. It sounds more formal than should.

Examples:

• You ought to be more careful with your money.

• They ought not to ignore the doctor’s instructions.

It is less common in modern spoken English, but still important in written or polite communication.

5. Shall – formal obligation or suggestion

Shall is used mainly in formal documents, rules, or legal writing to show obligation or requirement.

Examples:

• Tenants shall pay the rent by the first day of each month.

• All employees shall follow the company policy.

In British English, shall I / shall we is used to make polite suggestions.

Examples:

• Shall I close the window?

• Shall we start the presentation?

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