Modals are used before ordinary verbs and they express meanings such as permission, possibility, certainty and necessity. Modals are always accompanied by other verbs. Modals are never conjugated. Modals are followed by the ‘Present‘form of the verb.
Can - ‘Can’ is used to express permission, possibility, ability or capacity.
‘Can you try reading these words now?’
Could is used to express ability / capacity in the past, a polite request or a possibility under certain
‘Could you please stop quarrelling?’
‘Shall’ is used to express pure future with the first person, to ask for advice, suggestion, request etc.
with the first person in the interrogative or to express command, threat, warning, promise, assurance, determination etc. with the second and third person.
‘Should’ is used to express duty/ obligation or advisability or desirability, logical inference, supposition,
assumption, possibility, etc.
Example: ‘Mr. Sam, you should avoid climbing stairs as much as possible.’
‘May’ is used to express possibility, permission, wish, faith or hope
Example: ‘You may finish eating and then go for games.’
‘Might’ is used to express less possibility, permission or to express some guess.
‘Will’ is used to express pure future with second and third persons, willingness, intention, promise,
determination with the first person, characteristic habit, assumption, invitation or request and insistence.
‘Would’ is used to express past habits, a polite request, a wish, preference, or an imaginary condition.
Example: ‘I would become a famous pop singer one day.’
‘Must’ is used to express obligation or duty, necessity, compulsion or prohibition, emphatic advice or determination, assumption, conclusion / inference, certainty / strong probability, etc.
‘Ought to’ is used to express the subject’s obligation or duty or to give advice
‘Used to’ is used to express past habit
‘Need’ is used chiefly to show absence of necessity or compulsion in the negative and interrogative
“Dare” means “to have courage”.