I could heliograph you could heliograph he could heliograph we could heliograph you could heliograph they could heliograph
V-ing form
I could be heliographing you could be heliographing he could be heliographing we could be heliographing you could be heliographing they could be heliographing
Perfect
I could have heliographed you could have heliographed he could have heliographed we could have heliographed you could have heliographed they could have heliographed
V-ing perfect
I could have been heliographing you could have been heliographing he could have been heliographing we could have been heliographing you could have been heliographing they could have been heliographing
Negation
Simple form
I couldn't heliograph you couldn't heliograph he couldn't heliograph we couldn't heliograph you couldn't heliograph they couldn't heliograph
V-ing form
I couldn't be heliographing you couldn't be heliographing he couldn't be heliographing we couldn't be heliographing you couldn't be heliographing they couldn't be heliographing
Perfect
I couldn't have heliographed you couldn't have heliographed he couldn't have heliographed we couldn't have heliographed you couldn't have heliographed they couldn't have heliographed
V-ing perfect
I couldn't have been heliographing you couldn't have been heliographing he couldn't have been heliographing we couldn't have been heliographing you couldn't have been heliographing they couldn't have been heliographing
Interrogative form
Simple form
could I heliograph? could you heliograph? could he heliograph? could we heliograph? could you heliograph? could they heliograph?
V-ing form
could I be heliographing? could you be heliographing? could he be heliographing? could we be heliographing? could you be heliographing? could they be heliographing?
Perfect
could I have heliographed? could you have heliographed? could he have heliographed? could we have heliographed? could you have heliographed? could they have heliographed?
V-ing perfect
could I have been heliographing? could you have been heliographing? could he have been heliographing? could we have been heliographing? could you have been heliographing? could they have been heliographing?
Interro-negative form
Simple form
couldn't I heliograph? couldn't you heliograph? couldn't he heliograph? couldn't we heliograph? couldn't you heliograph? couldn't they heliograph?
V-ing form
couldn't I be heliographing? couldn't you be heliographing? couldn't he be heliographing? couldn't we be heliographing? couldn't you be heliographing? couldn't they be heliographing?
Perfect
couldn't I have heliographed? couldn't you have heliographed? couldn't he have heliographed? couldn't we have heliographed? couldn't you have heliographed? couldn't they have heliographed?
V-ing perfect
couldn't I have been heliographing? couldn't you have been heliographing? couldn't he have been heliographing? couldn't we have been heliographing? couldn't you have been heliographing? couldn't they have been heliographing?