should warn
Regular verb: warn - warned- warned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I'd warn
you'd warn
he'd warn
we'd warn
you'd warn
they'd warn 	I'd be warning
you'd be warning
he'd be warning
we'd be warning
you'd be warning
they'd be warning	I should've warned
you should've warned
he should've warned
we should've warned
you should've warned
they should've warned	I should've been warning
you should've been warning
he should've been warning
we should've been warning
you should've been warning
they should've been warning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I shouldn't warn
you shouldn't warn
he shouldn't warn
we shouldn't warn
you shouldn't warn
they shouldn't warn 	I shouldn't be warning
you shouldn't be warning
he shouldn't be warning
we shouldn't be warning
you shouldn't be warning
they shouldn't be warning	I shouldn't have warned
you shouldn't have warned
he shouldn't have warned
we shouldn't have warned
you shouldn't have warned
they shouldn't have warned	I shouldn't have been warning
you shouldn't have been warning
he shouldn't have been warning
we shouldn't have been warning
you shouldn't have been warning
they shouldn't have been warning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I warn?
should you warn?
should he warn?
should we warn?
should you warn?
should they warn? 	should I be warning?
should you be warning?
should he be warning?
should we be warning?
should you be warning?
should they be warning? 	should I have warned?
should you have warned?
should he have warned?
should we have warned?
should you have warned?
should they have warned? 	should I have been warning?
should you have been warning?
should he have been warning?
should we have been warning?
should you have been warning?
should they have been warning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
shouldn't I warn?
shouldn't you warn?
shouldn't he warn?
shouldn't we warn?
shouldn't you warn?
shouldn't they warn? 	shouldn't I be warning?
shouldn't you be warning?
shouldn't he be warning?
shouldn't we be warning?
shouldn't you be warning?
shouldn't they be warning? 	shouldn't I have warned?
shouldn't you have warned?
shouldn't he have warned?
shouldn't we have warned?
shouldn't you have warned?
shouldn't they have warned? 	shouldn't I have been warning?
shouldn't you have been warning?
shouldn't he have been warning?
shouldn't we have been warning?
shouldn't you have been warning?
shouldn't they have been warning?