should thicken
Regular verb: thicken - thickened- thickened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I'd thicken
you'd thicken
she'd thicken
we'd thicken
you'd thicken
they'd thicken 	I'd be thickening
you'd be thickening
she'd be thickening
we'd be thickening
you'd be thickening
they'd be thickening	I should've thickened
you should've thickened
she should've thickened
we should've thickened
you should've thickened
they should've thickened	I should've been thickening
you should've been thickening
she should've been thickening
we should've been thickening
you should've been thickening
they should've been thickening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I shouldn't thicken
you shouldn't thicken
she shouldn't thicken
we shouldn't thicken
you shouldn't thicken
they shouldn't thicken 	I shouldn't be thickening
you shouldn't be thickening
she shouldn't be thickening
we shouldn't be thickening
you shouldn't be thickening
they shouldn't be thickening	I shouldn't have thickened
you shouldn't have thickened
she shouldn't have thickened
we shouldn't have thickened
you shouldn't have thickened
they shouldn't have thickened	I shouldn't have been thickening
you shouldn't have been thickening
she shouldn't have been thickening
we shouldn't have been thickening
you shouldn't have been thickening
they shouldn't have been thickening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
should I thicken?
should you thicken?
should she thicken?
should we thicken?
should you thicken?
should they thicken? 	should I be thickening?
should you be thickening?
should she be thickening?
should we be thickening?
should you be thickening?
should they be thickening? 	should I have thickened?
should you have thickened?
should she have thickened?
should we have thickened?
should you have thickened?
should they have thickened? 	should I have been thickening?
should you have been thickening?
should she have been thickening?
should we have been thickening?
should you have been thickening?
should they have been thickening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
shouldn't I thicken?
shouldn't you thicken?
shouldn't she thicken?
shouldn't we thicken?
shouldn't you thicken?
shouldn't they thicken? 	shouldn't I be thickening?
shouldn't you be thickening?
shouldn't she be thickening?
shouldn't we be thickening?
shouldn't you be thickening?
shouldn't they be thickening? 	shouldn't I have thickened?
shouldn't you have thickened?
shouldn't she have thickened?
shouldn't we have thickened?
shouldn't you have thickened?
shouldn't they have thickened? 	shouldn't I have been thickening?
shouldn't you have been thickening?
shouldn't she have been thickening?
shouldn't we have been thickening?
shouldn't you have been thickening?
shouldn't they have been thickening?