should fail
Regular verb: fail - failed- failed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I'd fail
you'd fail
he'd fail
we'd fail
you'd fail
they'd fail 	I'd be failing
you'd be failing
he'd be failing
we'd be failing
you'd be failing
they'd be failing	I should've failed
you should've failed
he should've failed
we should've failed
you should've failed
they should've failed	I should've been failing
you should've been failing
he should've been failing
we should've been failing
you should've been failing
they should've been failing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I shouldn't fail
you shouldn't fail
he shouldn't fail
we shouldn't fail
you shouldn't fail
they shouldn't fail 	I shouldn't be failing
you shouldn't be failing
he shouldn't be failing
we shouldn't be failing
you shouldn't be failing
they shouldn't be failing	I shouldn't have failed
you shouldn't have failed
he shouldn't have failed
we shouldn't have failed
you shouldn't have failed
they shouldn't have failed	I shouldn't have been failing
you shouldn't have been failing
he shouldn't have been failing
we shouldn't have been failing
you shouldn't have been failing
they shouldn't have been failing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I fail?
should you fail?
should he fail?
should we fail?
should you fail?
should they fail? 	should I be failing?
should you be failing?
should he be failing?
should we be failing?
should you be failing?
should they be failing? 	should I have failed?
should you have failed?
should he have failed?
should we have failed?
should you have failed?
should they have failed? 	should I have been failing?
should you have been failing?
should he have been failing?
should we have been failing?
should you have been failing?
should they have been failing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
shouldn't I fail?
shouldn't you fail?
shouldn't he fail?
shouldn't we fail?
shouldn't you fail?
shouldn't they fail? 	shouldn't I be failing?
shouldn't you be failing?
shouldn't he be failing?
shouldn't we be failing?
shouldn't you be failing?
shouldn't they be failing? 	shouldn't I have failed?
shouldn't you have failed?
shouldn't he have failed?
shouldn't we have failed?
shouldn't you have failed?
shouldn't they have failed? 	shouldn't I have been failing?
shouldn't you have been failing?
shouldn't he have been failing?
shouldn't we have been failing?
shouldn't you have been failing?
shouldn't they have been failing?