This document discusses different types of modal verbs in English including those that express ability, requests and permission, obligation, prohibition, advice, and possibility. It notes that most modal verbs have the same form for all persons, do not use do/does for negatives or questions, and are followed by an infinitive without to. Examples are provided for each modal verb category.

1. ABILITY
Can
Could
Be able to
Present
Past
Future
REQUEST AND
PERMISION
May
Could
Can
Formal
Informal
OBLIGATION
Must Strong obligation
Have to / Need to
Don’t have to /
Don’t need to /
Needn’t
Lack of
obligation
PROHIBITION
Mustn’t
ADVICE
Should
Ought to
Had better
Should have + V3
POSSIBILITY
Must 90%
Can / May
Could / Might
50%
Can’t 0%
Past
Had better always contains
the suggestion of negative
consequences

2. General
Most modal verbs…
• have the same form for all persons:
I can, you can, he can…
•do not use do / does to form the negative or interrogative:
Must you came so late?
I shouldn’t be so lazy, etc.
•are followed by the infitive without to:
We must go, they should see, etc.