can stiff
Regular verb: stiff - stiffed- stiffed

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

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

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

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