■ modal verb ( 3rd singular ~ )
1》 used to indicate obligation, duty, or correctness.
↘used to give or ask advice or suggestions.
2》 used to indicate what is probable.
3》 formal expressing the conditional mood.
↘(in the first person) indicating the consequence of an imagined event.
↘referring to a possible event or situation.
4》 used in a clause with ‘that’ after a main clause describing feelings.
5》 used in a clause with ‘that’ expressing purpose.
6》 (in the first person) expressing a polite request or acceptance.
7》 (in the first person) expressing a conjecture or hope.
Origin
OE sceolde : past of shall .
Usage
As with shall and will , there are traditional rules about the use of ~ and would . These state that ~ is used with I and we ( I said I ~ be late ), while would is used with you , he , she , it , and they ( you didn't say you would be late ). However, these rules are no longer strictly followed and would is normally used instead of ~ in reported speech and conditional clauses: I said I would be late . In spoken and informal contexts the issue rarely arises, since the distinction is obscured by the use of the contracted forms I'd , we'd , etc.
For a discussion on the use of ~ of instead of ~ have , see usage at have .