I could isle you could isle she could isle we could isle you could isle they could isle
V-ing form
I could be isling you could be isling she could be isling we could be isling you could be isling they could be isling
Perfect
I could have isled you could have isled she could have isled we could have isled you could have isled they could have isled
V-ing perfect
I could have been isling you could have been isling she could have been isling we could have been isling you could have been isling they could have been isling
Negation
Simple form
I could not isle you could not isle she could not isle we could not isle you could not isle they could not isle
V-ing form
I could not be isling you could not be isling she could not be isling we could not be isling you could not be isling they could not be isling
Perfect
I could not have isled you could not have isled she could not have isled we could not have isled you could not have isled they could not have isled
V-ing perfect
I could not have been isling you could not have been isling she could not have been isling we could not have been isling you could not have been isling they could not have been isling
Interrogative form
Simple form
could I isle? could you isle? could she isle? could we isle? could you isle? could they isle?
V-ing form
could I be isling? could you be isling? could she be isling? could we be isling? could you be isling? could they be isling?
Perfect
could I have isled? could you have isled? could she have isled? could we have isled? could you have isled? could they have isled?
V-ing perfect
could I have been isling? could you have been isling? could she have been isling? could we have been isling? could you have been isling? could they have been isling?
Interro-negative form
Simple form
could I not isle? could you not isle? could she not isle? could we not isle? could you not isle? could they not isle?
V-ing form
could I not be isling? could you not be isling? could she not be isling? could we not be isling? could you not be isling? could they not be isling?
Perfect
could I not have isled? could you not have isled? could she not have isled? could we not have isled? could you not have isled? could they not have isled?
V-ing perfect
could I not have been isling? could you not have been isling? could she not have been isling? could we not have been isling? could you not have been isling? could they not have been isling?