English verb conjugation
SHOULD STIFF

Regular verb: stiff - stiffed - stiffed

Affirmation

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

Negation

Simple form	V-ing form
I should not stiff you should not stiff he should not stiff we should not stiff you should not stiff they should not stiff	I should not be stiffing you should not be stiffing he should not be stiffing we should not be stiffing you should not be stiffing they should not be stiffing
Perfect	V-ing perfect
I should not have stiffed you should not have stiffed he should not have stiffed we should not have stiffed you should not have stiffed they should not have stiffed	I should not have been stiffing you should not have been stiffing he should not have been stiffing we should not have been stiffing you should not have been stiffing they should not 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
should I not stiff? should you not stiff? should he not stiff? should we not stiff? should you not stiff? should they not stiff?	should I not be stiffing? should you not be stiffing? should he not be stiffing? should we not be stiffing? should you not be stiffing? should they not be stiffing?
Perfect	V-ing perfect
should I not have stiffed? should you not have stiffed? should he not have stiffed? should we not have stiffed? should you not have stiffed? should they not have stiffed?	should I not have been stiffing? should you not have been stiffing? should he not have been stiffing? should we not have been stiffing? should you not have been stiffing? should they not have been stiffing?