Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could scream scream you could scream scream he could scream scream we could scream scream you could scream scream they could scream scream
V-ing form
I could be scream screaming you could be scream screaming he could be scream screaming we could be scream screaming you could be scream screaming they could be scream screaming
Perfect
I could have scream screamed you could have scream screamed he could have scream screamed we could have scream screamed you could have scream screamed they could have scream screamed
V-ing perfect
I could have been scream screaming you could have been scream screaming he could have been scream screaming we could have been scream screaming you could have been scream screaming they could have been scream screaming
Negation
Simple form
I could not scream scream you could not scream scream he could not scream scream we could not scream scream you could not scream scream they could not scream scream
V-ing form
I could not be scream screaming you could not be scream screaming he could not be scream screaming we could not be scream screaming you could not be scream screaming they could not be scream screaming
Perfect
I could not have scream screamed you could not have scream screamed he could not have scream screamed we could not have scream screamed you could not have scream screamed they could not have scream screamed
V-ing perfect
I could not have been scream screaming you could not have been scream screaming he could not have been scream screaming we could not have been scream screaming you could not have been scream screaming they could not have been scream screaming
Interrogative form
Simple form
could I scream scream? could you scream scream? could he scream scream? could we scream scream? could you scream scream? could they scream scream?
V-ing form
could I be scream screaming? could you be scream screaming? could he be scream screaming? could we be scream screaming? could you be scream screaming? could they be scream screaming?
Perfect
could I have scream screamed? could you have scream screamed? could he have scream screamed? could we have scream screamed? could you have scream screamed? could they have scream screamed?
V-ing perfect
could I have been scream screaming? could you have been scream screaming? could he have been scream screaming? could we have been scream screaming? could you have been scream screaming? could they have been scream screaming?
Interro-negative form
Simple form
could I not scream scream? could you not scream scream? could he not scream scream? could we not scream scream? could you not scream scream? could they not scream scream?
V-ing form
could I not be scream screaming? could you not be scream screaming? could he not be scream screaming? could we not be scream screaming? could you not be scream screaming? could they not be scream screaming?
Perfect
could I not have scream screamed? could you not have scream screamed? could he not have scream screamed? could we not have scream screamed? could you not have scream screamed? could they not have scream screamed?
V-ing perfect
could I not have been scream screaming? could you not have been scream screaming? could he not have been scream screaming? could we not have been scream screaming? could you not have been scream screaming? could they not have been scream screaming?