I have seen some scenarios where we use 'to' after 'must'.

All languages are must to learn.

This usage is correct while,

You must to learn cooking.

This usage is wrong.

Why is it wrong in terms of meaning?

  • 1
    The syntax of your first example is invalid, because you need to include the article: All languages are a must to learn. But then there's a semantic problem, because it makes no sense to assert that it's necessary for a person to learn all languages. A valid example might be English is a must to learn, or even English and Chinese are a must to learn nowadays. Oct 15, 2021 at 12:28
  • The relevant usage here is must (noun) Something that should not be overlooked or missed (note - this sense is extremely uncommon as a plural). Oct 15, 2021 at 12:31
  • @FumbleFingers - bandages, antibiotics, and good running shoes are probably musts when you are starting to learn lion taming. Being intentional and competitive are musts when buying a home right now, recognizing and taking action are musts when it comes to controlling challenging behaviors with our children. Oct 15, 2021 at 13:23
  • @MichaelHarvey: I said the plural usage is uncommon, and there's no doubt that are musts practically flatlines in Google NGrams compared to the singular is a must. I certainly don't claim there's anything "invalid" about the plural - but per my first comment, I would actually prefer the singular in my own example. I'm afraid English and Chinese are musts to learn nowadays seems like a bit of a mouthful to me (it's too much trouble to articulate /s/). Oct 15, 2021 at 13:41

1 Answer 1


Must, like all modals, takes the base form of the following verb, not a to infinitive. Always.

Must is also a noun, meaning "something that you must have". Your first sentence needs "a", and says "Languages are a must to learn", or to turn it round "To learn languages is a must". Even with this nominal use of must, the to is not governed by it, but is a different constituent of the sentence.

  • 1
    I just love it when answers state things clearly. Yes, all modals must take the base form of the following verb.
    – Lambie
    Oct 15, 2021 at 13:41

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