should knuckle
Regular verb: knuckle - knuckled- knuckled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I'd knuckle
you'd knuckle
he'd knuckle
we'd knuckle
you'd knuckle
they'd knuckle 	I'd be knuckling
you'd be knuckling
he'd be knuckling
we'd be knuckling
you'd be knuckling
they'd be knuckling	I should've knuckled
you should've knuckled
he should've knuckled
we should've knuckled
you should've knuckled
they should've knuckled	I should've been knuckling
you should've been knuckling
he should've been knuckling
we should've been knuckling
you should've been knuckling
they should've been knuckling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I shouldn't knuckle
you shouldn't knuckle
he shouldn't knuckle
we shouldn't knuckle
you shouldn't knuckle
they shouldn't knuckle 	I shouldn't be knuckling
you shouldn't be knuckling
he shouldn't be knuckling
we shouldn't be knuckling
you shouldn't be knuckling
they shouldn't be knuckling	I shouldn't have knuckled
you shouldn't have knuckled
he shouldn't have knuckled
we shouldn't have knuckled
you shouldn't have knuckled
they shouldn't have knuckled	I shouldn't have been knuckling
you shouldn't have been knuckling
he shouldn't have been knuckling
we shouldn't have been knuckling
you shouldn't have been knuckling
they shouldn't have been knuckling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I knuckle?
should you knuckle?
should he knuckle?
should we knuckle?
should you knuckle?
should they knuckle? 	should I be knuckling?
should you be knuckling?
should he be knuckling?
should we be knuckling?
should you be knuckling?
should they be knuckling? 	should I have knuckled?
should you have knuckled?
should he have knuckled?
should we have knuckled?
should you have knuckled?
should they have knuckled? 	should I have been knuckling?
should you have been knuckling?
should he have been knuckling?
should we have been knuckling?
should you have been knuckling?
should they have been knuckling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
shouldn't I knuckle?
shouldn't you knuckle?
shouldn't he knuckle?
shouldn't we knuckle?
shouldn't you knuckle?
shouldn't they knuckle? 	shouldn't I be knuckling?
shouldn't you be knuckling?
shouldn't he be knuckling?
shouldn't we be knuckling?
shouldn't you be knuckling?
shouldn't they be knuckling? 	shouldn't I have knuckled?
shouldn't you have knuckled?
shouldn't he have knuckled?
shouldn't we have knuckled?
shouldn't you have knuckled?
shouldn't they have knuckled? 	shouldn't I have been knuckling?
shouldn't you have been knuckling?
shouldn't he have been knuckling?
shouldn't we have been knuckling?
shouldn't you have been knuckling?
shouldn't they have been knuckling?