I could invoke you could invoke he could invoke we could invoke you could invoke they could invoke
V-ing form
I could be invoking you could be invoking he could be invoking we could be invoking you could be invoking they could be invoking
Perfect
I could have invoked you could have invoked he could have invoked we could have invoked you could have invoked they could have invoked
V-ing perfect
I could have been invoking you could have been invoking he could have been invoking we could have been invoking you could have been invoking they could have been invoking
Negation
Simple form
I could not invoke you could not invoke he could not invoke we could not invoke you could not invoke they could not invoke
V-ing form
I could not be invoking you could not be invoking he could not be invoking we could not be invoking you could not be invoking they could not be invoking
Perfect
I could not have invoked you could not have invoked he could not have invoked we could not have invoked you could not have invoked they could not have invoked
V-ing perfect
I could not have been invoking you could not have been invoking he could not have been invoking we could not have been invoking you could not have been invoking they could not have been invoking
Interrogative form
Simple form
could I invoke? could you invoke? could he invoke? could we invoke? could you invoke? could they invoke?
V-ing form
could I be invoking? could you be invoking? could he be invoking? could we be invoking? could you be invoking? could they be invoking?
Perfect
could I have invoked? could you have invoked? could he have invoked? could we have invoked? could you have invoked? could they have invoked?
V-ing perfect
could I have been invoking? could you have been invoking? could he have been invoking? could we have been invoking? could you have been invoking? could they have been invoking?
Interro-negative form
Simple form
could I not invoke? could you not invoke? could he not invoke? could we not invoke? could you not invoke? could they not invoke?
V-ing form
could I not be invoking? could you not be invoking? could he not be invoking? could we not be invoking? could you not be invoking? could they not be invoking?
Perfect
could I not have invoked? could you not have invoked? could he not have invoked? could we not have invoked? could you not have invoked? could they not have invoked?
V-ing perfect
could I not have been invoking? could you not have been invoking? could he not have been invoking? could we not have been invoking? could you not have been invoking? could they not have been invoking?