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 couldn't scream you couldn't scream he couldn't scream we couldn't scream you couldn't scream they couldn't scream
V-ing form
I couldn't be screaming you couldn't be screaming he couldn't be screaming we couldn't be screaming you couldn't be screaming they couldn't be screaming
Perfect
I couldn't have screamed you couldn't have screamed he couldn't have screamed we couldn't have screamed you couldn't have screamed they couldn't have screamed
V-ing perfect
I couldn't have been screaming you couldn't have been screaming he couldn't have been screaming we couldn't have been screaming you couldn't have been screaming they couldn't 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
couldn't I scream? couldn't you scream? couldn't he scream? couldn't we scream? couldn't you scream? couldn't they scream?
V-ing form
couldn't I be screaming? couldn't you be screaming? couldn't he be screaming? couldn't we be screaming? couldn't you be screaming? couldn't they be screaming?
Perfect
couldn't I have screamed? couldn't you have screamed? couldn't he have screamed? couldn't we have screamed? couldn't you have screamed? couldn't they have screamed?
V-ing perfect
couldn't I have been screaming? couldn't you have been screaming? couldn't he have been screaming? couldn't we have been screaming? couldn't you have been screaming? couldn't they have been screaming?