English verb conjugation
COULD SCREW

Regular verb: screw - screwed - screwed

Affirmation

Simple form	V-ing form
I could screw you could screw he could screw we could screw you could screw they could screw	I could be screwing you could be screwing he could be screwing we could be screwing you could be screwing they could be screwing
Perfect	V-ing perfect
I could have screwed you could have screwed he could have screwed we could have screwed you could have screwed they could have screwed	I could have been screwing you could have been screwing he could have been screwing we could have been screwing you could have been screwing they could have been screwing

Negation

Simple form	V-ing form
I could not screw you could not screw he could not screw we could not screw you could not screw they could not screw	I could not be screwing you could not be screwing he could not be screwing we could not be screwing you could not be screwing they could not be screwing
Perfect	V-ing perfect
I could not have screwed you could not have screwed he could not have screwed we could not have screwed you could not have screwed they could not have screwed	I could not have been screwing you could not have been screwing he could not have been screwing we could not have been screwing you could not have been screwing they could not have been screwing

Interrogative form

Simple form	V-ing form
could I screw? could you screw? could he screw? could we screw? could you screw? could they screw?	could I be screwing? could you be screwing? could he be screwing? could we be screwing? could you be screwing? could they be screwing?
Perfect	V-ing perfect
could I have screwed? could you have screwed? could he have screwed? could we have screwed? could you have screwed? could they have screwed?	could I have been screwing? could you have been screwing? could he have been screwing? could we have been screwing? could you have been screwing? could they have been screwing?

Interro-negative form

Simple form	V-ing form
could I not screw? could you not screw? could he not screw? could we not screw? could you not screw? could they not screw?	could I not be screwing? could you not be screwing? could he not be screwing? could we not be screwing? could you not be screwing? could they not be screwing?
Perfect	V-ing perfect
could I not have screwed? could you not have screwed? could he not have screwed? could we not have screwed? could you not have screwed? could they not have screwed?	could I not have been screwing? could you not have been screwing? could he not have been screwing? could we not have been screwing? could you not have been screwing? could they not have been screwing?