English verb conjugation
SHOULD STIFF

Regular verb: stiff - stiffed - stiffed

Affirmation

Simple form	V-ing form
I'd stiff you'd stiff he'd stiff we'd stiff you'd stiff they'd stiff	I'd be stiffing you'd be stiffing he'd be stiffing we'd be stiffing you'd be stiffing they'd be stiffing
Perfect	V-ing perfect
I should've stiffed you should've stiffed he should've stiffed we should've stiffed you should've stiffed they should've stiffed	I should've been stiffing you should've been stiffing he should've been stiffing we should've been stiffing you should've been stiffing they should've been stiffing

Negation

Simple form	V-ing form
I shouldn't stiff you shouldn't stiff he shouldn't stiff we shouldn't stiff you shouldn't stiff they shouldn't stiff	I shouldn't be stiffing you shouldn't be stiffing he shouldn't be stiffing we shouldn't be stiffing you shouldn't be stiffing they shouldn't be stiffing
Perfect	V-ing perfect
I shouldn't have stiffed you shouldn't have stiffed he shouldn't have stiffed we shouldn't have stiffed you shouldn't have stiffed they shouldn't have stiffed	I shouldn't have been stiffing you shouldn't have been stiffing he shouldn't have been stiffing we shouldn't have been stiffing you shouldn't have been stiffing they shouldn't have been stiffing

Interrogative form

Simple form	V-ing form
should I stiff? should you stiff? should he stiff? should we stiff? should you stiff? should they stiff?	should I be stiffing? should you be stiffing? should he be stiffing? should we be stiffing? should you be stiffing? should they be stiffing?
Perfect	V-ing perfect
should I have stiffed? should you have stiffed? should he have stiffed? should we have stiffed? should you have stiffed? should they have stiffed?	should I have been stiffing? should you have been stiffing? should he have been stiffing? should we have been stiffing? should you have been stiffing? should they have been stiffing?

Interro-negative form

Simple form	V-ing form
shouldn't I stiff? shouldn't you stiff? shouldn't he stiff? shouldn't we stiff? shouldn't you stiff? shouldn't they stiff?	shouldn't I be stiffing? shouldn't you be stiffing? shouldn't he be stiffing? shouldn't we be stiffing? shouldn't you be stiffing? shouldn't they be stiffing?
Perfect	V-ing perfect
shouldn't I have stiffed? shouldn't you have stiffed? shouldn't he have stiffed? shouldn't we have stiffed? shouldn't you have stiffed? shouldn't they have stiffed?	shouldn't I have been stiffing? shouldn't you have been stiffing? shouldn't he have been stiffing? shouldn't we have been stiffing? shouldn't you have been stiffing? shouldn't they have been stiffing?