The most common modal verbs are often associated with the following uses:
- Can, Could, Be Able to – Are used to express ability, possibility, ask or give permission, offer suggestions.
- May/Might – Are commonly used to offer formal permission or the opposite; a polite request and suggestion, possibility and make a suggestion.
- Shall/Should – Are commonly used to offer advice, make prediction and offer assistance or polite suggestion
- Must, Have to, Need to – Used to show a requirement or necessity, past, to persuade or convince, show something is forbidden
- Will/would – Are normally used in polite requests and statements, habitual actions in the past