Intermediate Grammar – Must, To have to


(that’s “Hello” in Russian).

The following lesson is for intermediate students. If you are not sure of your English level, take our test!

You can find all this information, plus speaking, writing, vocabulary exercises and more on the ABA English Course Unit 54 – A small argument.

When to use must and to have to

We use “must” and “to have to” to say that it is necessary or obligatory to do something. Often, when speaking in the affirmative, it doesn’t matter which one we decide to use.

For example:

“I must go to the bank before it closes”

“I have to go to the bank before it closes”

These two sentence mean almost the same thing. The only difference is that “must” indicates strong obligation.

But, be careful! There is a big difference beteween “must” and “have to” in the negative form. We use “must not”, or its contraction “mustn’t”, in the negative form to express a strong obligation not to do something.

For example:

“You mustn’t leave the gas on when you leave the house!”

We use “do not have to” or “does not have to”, or the contractions “don’t have to” or “doesn’t have to”, to say there is no obligation or that something is not necessary.

For example:

“He doesn’t work until 2pm, so he doesn’t have to get up early”

See? “Must” and “have to” have very different meanings!

The modal verb must

Do you remember what you learned about modal verbs in unit 49? Let’s start with an example:

“It’s late. I must go to bed!”

Must is a modal verb. This means it precedes other verbs. Also, the third person singular does not end in -s, the inifinite form is not preceded by “to” and it does not need the auxiliary forms “do” and “does” in questions and interrogative sentences.

The verb to have to

“To have to” is not a modal verb, so it does change in the third person singular.

For example:

“He starts early, so he has to get up at 6am”

The infinitive form is “to have to” and it uses the auxiliary forms “do” and “does” in questions and negative sentences.

Unit 54 – A small argument

Excellent! You just revised the grammar from Unit 54!


In Unit 54 – A small argument, you will meet a husband and wife. They are talking about who has to take the kids to school the next day.

By watching ABA Films, you will practice your listening comprehension. Record your voice and compare phrases to improve your pronunciation and gain fluency by interpreting different roles. You will also learn new vocabulary and review the unit’s grammar lesson.

Did you enjoy this class? TWEET IT OUT: I reviewed how to use must and to have to with @abaenglish on their blog #esl

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