I could haven you could haven she could haven we could haven you could haven they could haven
V-ing form
I could be havening you could be havening she could be havening we could be havening you could be havening they could be havening
Perfect
I could have havened you could have havened she 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 she 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 she 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 she 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 she 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 she 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 she haven? could we haven? could you haven? could they haven?
V-ing form
could I be havening? could you be havening? could she be havening? could we be havening? could you be havening? could they be havening?
Perfect
could I have havened? could you have havened? could she 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 she 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 she 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 she 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 she 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 she have been havening? couldn't we have been havening? couldn't you have been havening? couldn't they have been havening?