Ability, Admission and Advice
Basic Modals
Modals verbs modify principal verbs to express various degrees of modality such as necessity, permission, etc. . The most common modals are:
Can
Should
He can write the press release.
She should spend more time determining the ecological impact.
Modal verbs remain in base form for all subjects.
Positive Form:
Subject + Modal + Verb + objects
He can write the press release.
She should spend more time determining the ecological impact.
Negative Form:
Subject + Modal + Not + Verb + objects
William can't have been interested in that social enterprise.
Jason shouldn't claim impartiality if he has a financial interest.
Question Form:
Modal + Subject + Verb + objects
Can you state the basic principle?
Should we begin the implementation process?
Can for Ability and Permission
'Can' is used to speak about abilities as well as asking for or giving permission.
Giving Advice with Should
Use 'Should' to ask for or give advice or suggestions.
Ought to, Had Better
'Ought to' and 'had better' express the same idea as 'should'. Although not as common as 'should' both these forms can be used in place of 'should'.
Example:
We ought to file the progress report by Friday.
We had better discover a new indicator.
NOTE: 'had better' is a more urgent form.