Modal Verbs of Obligation

Modal Verbs of Obligation

Hello, English learners. Welcome to a new lesson. Grammar is an essential part of any language. It is the cement that holds a language together. Modal verbs are special verbs in the English language. We use them to express modality. They help a lot when we discuss permission, ability, making requests, and so on. In today’s lesson, we will discuss modal verbs of obligation. Modal verbs of obligation are must, have to and should.

Must

The modal verb must express a strong obligation.

• You must stop at the red light.
• Children must be quiet to avoid disturbing the neighbours.
• Everyone must obey the school rules!
• We must find a solution to this problem. Let’s have a brainstorming meeting.

Learn more about the modal verb must here

Negative of must is mustn’t. Remember not to use auxiliary verbs with must. We use mustn’t to give very strong advice or to say that something is forbidden.

• You must tell the truth, you mustn’t lie.
• Hurry up, we mustn’t be late.
• Watch your mouth! You mustn’t talk like that!

Must can only be used in the present tense. For other verb forms, we use have to instead of must.

• Sofia had to wear a uniform when she was a primary school student.
• You’ll have to pay the bill. We don’t have any money.

Modal verbs of obligation

Have to

Have to is very similar to must. Must is used to express specific obligations, while have to expresses general ones.

• You must be able to speak English to be considered for this job.
• Elsa is a single mother of two toddlers, so she has to cook every day.

Don’t have to/doesn’t have to are used to express the absence of obligation.

• You don’t have to knock, just get in.
• Liam doesn’t have to work at weekends.

Modal verbs of obligation

Should

We use the modal verb should to give recommendations and advice.

Read about modal verbs of advice here

• You should do your homework and study regularly.
• You should never judge people by their looks.
• Every citizen should obey these rules.

Negative of should is shouldn’t.

• You shouldn’t buy that car unless you’ve tried it.
• You shouldn’t waste your time. 

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