English verb conjugation
COULD STIFFER

Regular verb: stiffer - stiffered - stiffered

Warning, this verb may not exist. Conjugation is given as example.

Affirmation

Simple form	V-ing form
I could stiffer you could stiffer he could stiffer we could stiffer you could stiffer they could stiffer	I could be stiffering you could be stiffering he could be stiffering we could be stiffering you could be stiffering they could be stiffering
Perfect	V-ing perfect
I could have stiffered you could have stiffered he could have stiffered we could have stiffered you could have stiffered they could have stiffered	I could have been stiffering you could have been stiffering he could have been stiffering we could have been stiffering you could have been stiffering they could have been stiffering

Negation

Simple form	V-ing form
I couldn't stiffer you couldn't stiffer he couldn't stiffer we couldn't stiffer you couldn't stiffer they couldn't stiffer	I couldn't be stiffering you couldn't be stiffering he couldn't be stiffering we couldn't be stiffering you couldn't be stiffering they couldn't be stiffering
Perfect	V-ing perfect
I couldn't have stiffered you couldn't have stiffered he couldn't have stiffered we couldn't have stiffered you couldn't have stiffered they couldn't have stiffered	I couldn't have been stiffering you couldn't have been stiffering he couldn't have been stiffering we couldn't have been stiffering you couldn't have been stiffering they couldn't have been stiffering

Interrogative form

Simple form	V-ing form
could I stiffer? could you stiffer? could he stiffer? could we stiffer? could you stiffer? could they stiffer?	could I be stiffering? could you be stiffering? could he be stiffering? could we be stiffering? could you be stiffering? could they be stiffering?
Perfect	V-ing perfect
could I have stiffered? could you have stiffered? could he have stiffered? could we have stiffered? could you have stiffered? could they have stiffered?	could I have been stiffering? could you have been stiffering? could he have been stiffering? could we have been stiffering? could you have been stiffering? could they have been stiffering?

Interro-negative form

Simple form	V-ing form
couldn't I stiffer? couldn't you stiffer? couldn't he stiffer? couldn't we stiffer? couldn't you stiffer? couldn't they stiffer?	couldn't I be stiffering? couldn't you be stiffering? couldn't he be stiffering? couldn't we be stiffering? couldn't you be stiffering? couldn't they be stiffering?
Perfect	V-ing perfect
couldn't I have stiffered? couldn't you have stiffered? couldn't he have stiffered? couldn't we have stiffered? couldn't you have stiffered? couldn't they have stiffered?	couldn't I have been stiffering? couldn't you have been stiffering? couldn't he have been stiffering? couldn't we have been stiffering? couldn't you have been stiffering? couldn't they have been stiffering?