I could scream you could scream he could scream we could scream you could scream they could scream
V-ing form
I could be screaming you could be screaming he could be screaming we could be screaming you could be screaming they could be screaming
Perfect
I could have screamed you could have screamed he could have screamed we could have screamed you could have screamed they could have screamed
V-ing perfect
I could have been screaming you could have been screaming he could have been screaming we could have been screaming you could have been screaming they could have been screaming
Negation
Simple form
I could not scream you could not scream he could not scream we could not scream you could not scream they could not scream
V-ing form
I could not be screaming you could not be screaming he could not be screaming we could not be screaming you could not be screaming they could not be screaming
Perfect
I could not have screamed you could not have screamed he could not have screamed we could not have screamed you could not have screamed they could not have screamed
V-ing perfect
I could not have been screaming you could not have been screaming he could not have been screaming we could not have been screaming you could not have been screaming they could not have been screaming
Interrogative form
Simple form
could I scream? could you scream? could he scream? could we scream? could you scream? could they scream?
V-ing form
could I be screaming? could you be screaming? could he be screaming? could we be screaming? could you be screaming? could they be screaming?
Perfect
could I have screamed? could you have screamed? could he have screamed? could we have screamed? could you have screamed? could they have screamed?
V-ing perfect
could I have been screaming? could you have been screaming? could he have been screaming? could we have been screaming? could you have been screaming? could they have been screaming?
Interro-negative form
Simple form
could I not scream? could you not scream? could he not scream? could we not scream? could you not scream? could they not scream?
V-ing form
could I not be screaming? could you not be screaming? could he not be screaming? could we not be screaming? could you not be screaming? could they not be screaming?
Perfect
could I not have screamed? could you not have screamed? could he not have screamed? could we not have screamed? could you not have screamed? could they not have screamed?
V-ing perfect
could I not have been screaming? could you not have been screaming? could he not have been screaming? could we not have been screaming? could you not have been screaming? could they not have been screaming?