Modal Verbs & Auxiliary Verbs

Epistemic modality: degrees of certainty

must (certain) > should (probable) > may/might (possible) > could (less certain)

Deontic modality: obligation and permission

must/have to (obligation) / should/ought to (recommendation) / may (permission)

be about to — imminent action

She's about to leave / I was about to call you — it will happen very soon

be bound to / be likely to

It's bound to rain / She's likely to succeed — high probability expressions

can't help + -ing

I can't help laughing / She can't help feeling nervous — involuntary action

may well / might well

This may well be the solution / She might well be right — stronger possibility

Distancing modals in academic writing

The results could suggest... / This might indicate... — hedging claims in writing

would — habitual past in narrative

Every Sunday, she would bake bread / He would always whistle — past narrative

Modal + passive: should be done

This should be done carefully / It must be completed by Friday / It can be seen

be to + infinitive — formal future

The president is to visit next week / Talks are to resume tomorrow — official