Modals with “Not”: Must not, Do not have to (2024)

FAQs

Modals with “Not”: Must not, Do not have to? ›

The verbs “do not have to” and “must not” are modal verbs. Modal verbs are helping/auxiliary verbs that express ideas like ability, necessity, lack of obligation, and prohibition. Many modal verbs have more than one meaning. They are always followed by the simple form of a verb.

Used as a syntaxic category, it only refers to the single-word verbs can, could, may, might, must, shall, should, will, would. Used as a semantic category, it includes the single word modals plus other verbs which express modality in the same way.

We can use must and mustn't to talk about rules and obligations. I must do my homework. We must wear our school uniform.

"Mustn't" is a contraction of "must not" and is used to express a prohibition or something that is not allowed. For example, "You mustn't smoke in this area" means that smoking is prohibited and not allowed in that area. "Don't have to" is used to express that something is not necessary, but is allowed.

The main modal verbs are will, would, can, could, may, might, shall, should, must and ought. A modal verb only has finite forms and has no suffixes (e.g. I sing – he sings, but not I must – he musts).

Modals of Prohibition

Finally, in order to show that something is prohibited or not allowed, we use “must not.” For example: Students must not copy their work from the Internet. It's illegal! Children, you must not go in a stranger's car.

We use mustn't particularly when the prohibition comes from the speaker. (Parent to child) You mustn't say things like that to your sister. (Teacher to student) You mustn't be late to class. I mustn't let that happen again.

Must is a modal verb. It is followed by the base form of a verb. You use must to indicate that you think it is very important or necessary for something to happen.

What are two examples of must not? ›

short form of must not: You mustn't worry too much about this. You mustn't go into the garden. Tell them they mustn't make too much noise.

The opposite is 'must not' or 'mustn't'. We use this to talk about thinks we need to avoid doing. For example 'I mustn't drink too much beer at this party'. In this sentence, we can see that I don't think it is a good idea to drink too much beer at the party and want to avoid doing it.

In that context, "must" and "can" have very different meanings: you must not even touch it means "you are not permitted to touch it", or "you risk some awful consequence if you touch it", whereas "you cannot even touch it (note that "cannot" is one word, not two) means "it is not possible for you to touch it".

Must is a modal verb. Examples with must: Passengers must present their tickets to the ticket officer. You must remember to submit the documents by the deadline.

We don't have to clean the car. They don't have to eat pizza. He doesn't have to work tomorrow. She doesn't have to go today.

The modal verbs “must,” “have to” and “have got to” show that something is not optional; it is necessary. Must is the strongest and most serious modal verb of the three and is most common in writing. It is unusual to use “must” in questions. I must study tonight.

Obligation Modal Verbs: These verbs are used to express the speaker's opinion about whether or not something is obligatory. The most common obligation modal verbs are “must” and “should.” Possibility Modal Verbs: These verbs are used to express the speaker's opinion about the possibility of something happening.

Modals of obligations example sentences; You must stop here. You have to wear a seatbelt when you drive. You must answer at least one question. You should call Mary.

Examples: “You must do your homework every night.” (Because I say you must!) “I must stop smoking!” (Because I think it's a good idea to stop.) Remember that “must” is a modal auxiliary verb.

When you are morally or legally bound to a particular commitment, it's your obligation to follow through on it. If you see a crime taking place, for example, it's your obligation to notify the police. If an elderly person comes onto a full bus, it's your obligation to give up your seat for him.