Shall vs Must

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What’s the difference between them?



Shall is an auxiliary verb used for expressing obligation, necessity, or duty. It is also used to express determination or intention.


1. Shall we meet at the park for lunch?

2. I shall take care of the matter immediately.

3. Thou shalt not steal.



Must is an auxiliary verb that is used to express obligation, necessity, or determination.


1. I must finish my essay by tomorrow morning.

2. You must always remember to be kind.

3. He must have forgotten his keys again.

Learn similar and opposite words to spot the difference




1. Must

2. Will

3. Ought to

4. Need to

5. Going to

1. Must not

2. Will not

3. Refuse

4. Deny

5. Abstain from


1. Need

2. Have to

3. Imperative

4. Require

5. Compulsory

1. May

2. Shall not

3. Refrain

4. Deny

5. Prohibit

Tricks for mastery

Useful tips to understand the difference between confusing words "Shall", "Must".

1. Remember that must is more general term.

2. Remember that shall is mostly used in legal contexts.

Practice English with the Promova app and avoid misusing confusing words

Frequently asked questions

In what situations should the 'shall' be used?

Shall should be used in legal contexts to express an obligation, necessity, or duty, and to express determination or intention.

When is the appropriate context for using the word 'must'?

Must is used to express an obligation, necessity, or determination.

Do the two words share the same pronunciation?

No, shall is pronounced /∫el/, while must is pronounced /mʌst/.

What are some common mistakes people make when using these words?

A common mistake people make when using shall and must is confusing them, as they have similar meanings. People might also use shall or must inappropriately in a sentence, not taking into account the context of the statement.

Fill in the gaps to check yourself

1. We _______ complete the assignment before the deadline.

2. By law, everyone _______ wear a seatbelt while driving.

3. I _______ be there for you whenever you need me.

4. The tenant _______ pay the rent by the first of every month.

5. All members _______ attend the mandatory meeting tomorrow.

6. You _______ not pass this gate without permission.

1. must

Explanation: The sentence conveys an obligation or necessity to complete the assignment on time. Must is commonly used in such contexts.

2. shall

Explanation: The use of by law hints at a legal context, making shall the more appropriate choice as it is often used in legal terms to express obligation.

3. shall

Explanation: The context is one of determination or intention to be there for someone, which aligns well with the usage of shall to express determination.

4. must

Explanation: This sentence conveys an obligation for the tenant to pay rent, making must a fitting choice.

5. shall

Explanation: Mandatory in this context implies a strong necessity, and shall is often used in formal rules or regulations, making it a suitable choice here.

6. shall

Explanation: The prohibition or restriction in accessing the gate sounds formal and authoritative, making shall a more appropriate fit in this context.

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List of Commonly Confused Words

Finding your way around the English language can be hard, especially since there are so many confusing words and rules. So, a list of the most confusing words in English is an extremely useful tool for improving language accuracy and sharing the ideas clearly.