I could leave you could leave she could leave we could leave you could leave they could leave
V-ing form
I could be leaving you could be leaving she could be leaving we could be leaving you could be leaving they could be leaving
Perfect
I could have left you could have left she could have left we could have left you could have left they could have left
V-ing perfect
I could have been leaving you could have been leaving she could have been leaving we could have been leaving you could have been leaving they could have been leaving
Negation
Simple form
I couldn't leave you couldn't leave she couldn't leave we couldn't leave you couldn't leave they couldn't leave
V-ing form
I couldn't be leaving you couldn't be leaving she couldn't be leaving we couldn't be leaving you couldn't be leaving they couldn't be leaving
Perfect
I couldn't have left you couldn't have left she couldn't have left we couldn't have left you couldn't have left they couldn't have left
V-ing perfect
I couldn't have been leaving you couldn't have been leaving she couldn't have been leaving we couldn't have been leaving you couldn't have been leaving they couldn't have been leaving
Interrogative form
Simple form
could I leave? could you leave? could she leave? could we leave? could you leave? could they leave?
V-ing form
could I be leaving? could you be leaving? could she be leaving? could we be leaving? could you be leaving? could they be leaving?
Perfect
could I have left? could you have left? could she have left? could we have left? could you have left? could they have left?
V-ing perfect
could I have been leaving? could you have been leaving? could she have been leaving? could we have been leaving? could you have been leaving? could they have been leaving?
Interro-negative form
Simple form
couldn't I leave? couldn't you leave? couldn't she leave? couldn't we leave? couldn't you leave? couldn't they leave?
V-ing form
couldn't I be leaving? couldn't you be leaving? couldn't she be leaving? couldn't we be leaving? couldn't you be leaving? couldn't they be leaving?
Perfect
couldn't I have left? couldn't you have left? couldn't she have left? couldn't we have left? couldn't you have left? couldn't they have left?
V-ing perfect
couldn't I have been leaving? couldn't you have been leaving? couldn't she have been leaving? couldn't we have been leaving? couldn't you have been leaving? couldn't they have been leaving?