I can leave you can leave he can leave we can leave you can leave they can leave
V-ing form
I can be leaving you can be leaving he can be leaving we can be leaving you can be leaving they can be leaving
Perfect
I can have left you can have left he can have left we can have left you can have left they can have left
V-ing perfect
I can have been leaving you can have been leaving he can have been leaving we can have been leaving you can have been leaving they can have been leaving
Negation
Simple form
I cannot leave you cannot leave he cannot leave we cannot leave you cannot leave they cannot leave
V-ing form
I cannot be leaving you cannot be leaving he cannot be leaving we cannot be leaving you cannot be leaving they cannot be leaving
Perfect
I cannot have left you cannot have left he cannot have left we cannot have left you cannot have left they cannot have left
V-ing perfect
I cannot have been leaving you cannot have been leaving he cannot have been leaving we cannot have been leaving you cannot have been leaving they cannot have been leaving
Interrogative form
Simple form
can I leave? can you leave? can he leave? can we leave? can you leave? can they leave?
V-ing form
can I be leaving? can you be leaving? can he be leaving? can we be leaving? can you be leaving? can they be leaving?
Perfect
can I have left? can you have left? can he have left? can we have left? can you have left? can they have left?
V-ing perfect
can I have been leaving? can you have been leaving? can he have been leaving? can we have been leaving? can you have been leaving? can they have been leaving?
Interro-negative form
Simple form
can I not leave? can you not leave? can he not leave? can we not leave? can you not leave? can they not leave?
V-ing form
can I not be leaving? can you not be leaving? can he not be leaving? can we not be leaving? can you not be leaving? can they not be leaving?
Perfect
can I not have left? can you not have left? can he not have left? can we not have left? can you not have left? can they not have left?
V-ing perfect
can I not have been leaving? can you not have been leaving? can he not have been leaving? can we not have been leaving? can you not have been leaving? can they not have been leaving?