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6.5.6: Should not/Must not/Don't Have to

  • Page ID
    271297
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    Modals with “Not”: Should Not, Must Not, Do Not Have to-UVIC

    Introduction

    Negative Modal of Advice

    Should not

    • In order to show that something is not advisable (a bad idea) we can use “should not” or “shouldn’t”

    For example:

    • You shouldn’t stay up too late the night before a test.

    Modals for Lack of Obligation

    • If something is not necessary or not an obligation, we use the modal verb “do/does not have to.” Make sure the verb agrees with the subject.

    For example:

    • In the United States, children do not have to go to school on Saturdays, but many adults have to work.

    Common Question: Do children have to go to school on Saturdays? No, they don't.

    Negative Question: Don't children have to go to school on Saturdays? No, they don't.

    • Maggie doesn't have to study tonight because she studied all day.

    Common Question: Does Maggie have to study tonight? No, she doesn't.

    Negative Question: Doesn't Maggie have to study tonight? No, she doesn't.

    To put the modal in past tense, simply use the phrase “DID not have to.”

    For example:

    • For homework last night, we had to read Units 4 and 6, but we didn't have to read Unit 5

    Question: Did we have to read Unit 5 last night? No, we didn’t.

    As always, modals are followed by the simple form of a verb. The “to” in “do not have to” is not an infinitive. It is part of the modal itself.

    Subject + do/does not have to + simple verb + ...

    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. It's dangerous!

    Using “must not” is very serious and not very common in North American English. There is no question form or past tense form. It is useful when people in authority are giving instructions or explaining to people what they must not do in a formal way. It is more common in writing than in speaking.

    • Drivers must not drive on the left side of the road in North America.
    • You must not drink alcohol before you drive. You could cause an accident.

    Note: In American English “mustn’t” is generally not used.

    Modals with "Not": Must Not Do not Have To from UVIC is licensed for use under CC BY-NC-SA 4.0 International.


    6.5.6: Should not/Must not/Don't Have to is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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