Modal Verbs of Necessity

Exercises

Explanation

At the B1 level, the most commonly used verbs of necessity are must, have to, need to, ought to, and shall (mainly in formal English).

1. Must – strong personal obligation or internal necessity

Must is used when the speaker feels that something is very important. The obligation comes from inside the speaker—from their personal beliefs, judgement, or sense of duty.

Examples:

• I must organise my notes today; they are completely disordered.

• You must wear gloves in the laboratory to protect yourself.

Negative form: must not (mustn’t)

The negative form expresses prohibition—something is not allowed.

Examples:

• You mustn’t enter this area; it’s unsafe.

• Students mustn’t leave class without permission.

Important: Must does not have a past form. For past obligations, we use had to.

2. Have to – external rules or requirements

Have to refers to obligations that come from outside—from rules, laws, schedules, or someone else’s expectations. The speaker is not choosing the obligation; it is imposed by the situation.

Examples:

• I have to attend the training because my company requires it.

• Drivers have to stop when the traffic light is red.

Tense forms:

• Present: I have to leave for work at 8.

• Past: I had to replace my ID card last month.

• Future: I will have to finish the report tomorrow.

Have got to – informal British English alternative

Used only in the present and mostly in spoken English.

Examples:

• I’ve got to call the dentist before noon.

• We’ve got to hurry or we’ll miss the train.

3. Need to – practical or situational necessity

Need to describes something that is necessary because of the situation, circumstances, or because it leads to a better outcome.

Examples:

• You need to update your software regularly to avoid problems.

• She needs to take a break; she has been working for hours.

Negative forms:

• You don’t need to print the form; an electronic copy is fine.

• He doesn’t need to bring lunch; food is provided.

In British English, we sometimes use needn’t (need not):

• You needn’t buy extra water; we already have plenty.

4. Ought to – moral advice or polite recommendation

Ought to expresses a sense of moral responsibility, correct behaviour, or a strong recommendation. It is more formal than should.

Examples:

• You ought to check your work before submitting it.

• They ought not to ignore these warning signs.

Though less common in everyday speech, it remains useful in polite or formal communication.

5. Shall – formal obligation or polite suggestion

Shall is mainly used in legal texts, contracts, or formal rules to show obligation or requirement.

Examples:

• The organisation shall provide safety equipment to all workers.

• All members shall follow the club regulations.

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

Examples:

• Shall I turn on the projector?

• Shall we continue with the next topic?

Quick Comparison Table

Understanding modal verbs of necessity helps you communicate clearly about rules, responsibilities, and essential actions. Knowing when to use must, have to, and need to will make your English more accurate and confident.