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