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