Modals of Obligation


Must: L

Used for: formal rules (UK+US) (also prohibitions – mustn’t)


Logical conclusions (UK+US): e.g. I’ve heard it from 6 manager students so it MUST be true.


UK: Self-imposed obligations, e.g.

Sorry, I really must be going now.





Have to: J

General obligations from outside of you


= muset in Czech, also good for nemuset

I don’t have to think!

[need to is a slightly softer version of have to, so it’s good for polite commands]


US: Self-imposed obligations, e.g. Sorry, I have to go now.





Should: L

Recommendations, moral obligations


e.g. You should stop complaining about your wonderful English teachers J


I should have visited my grandmother more often. She died in 1985.

[Ought to works exactly like should]




To be supposed to: J

Used when you are expected to do something or you have agreed to do it.


e.g. The bus was supposed to have arrived at 5 pm but it is already 3 hours late.


I was supposed to help my mum with the tidying up but I got distracted talking with Gotye on Skype.