I could confirm you could confirm she could confirm we could confirm you could confirm they could confirm
V-ing form
I could be confirming you could be confirming she could be confirming we could be confirming you could be confirming they could be confirming
Perfect
I could have confirmed you could have confirmed she could have confirmed we could have confirmed you could have confirmed they could have confirmed
V-ing perfect
I could have been confirming you could have been confirming she could have been confirming we could have been confirming you could have been confirming they could have been confirming
Negation
Simple form
I could not confirm you could not confirm she could not confirm we could not confirm you could not confirm they could not confirm
V-ing form
I could not be confirming you could not be confirming she could not be confirming we could not be confirming you could not be confirming they could not be confirming
Perfect
I could not have confirmed you could not have confirmed she could not have confirmed we could not have confirmed you could not have confirmed they could not have confirmed
V-ing perfect
I could not have been confirming you could not have been confirming she could not have been confirming we could not have been confirming you could not have been confirming they could not have been confirming
Interrogative form
Simple form
could I confirm? could you confirm? could she confirm? could we confirm? could you confirm? could they confirm?
V-ing form
could I be confirming? could you be confirming? could she be confirming? could we be confirming? could you be confirming? could they be confirming?
Perfect
could I have confirmed? could you have confirmed? could she have confirmed? could we have confirmed? could you have confirmed? could they have confirmed?
V-ing perfect
could I have been confirming? could you have been confirming? could she have been confirming? could we have been confirming? could you have been confirming? could they have been confirming?
Interro-negative form
Simple form
could I not confirm? could you not confirm? could she not confirm? could we not confirm? could you not confirm? could they not confirm?
V-ing form
could I not be confirming? could you not be confirming? could she not be confirming? could we not be confirming? could you not be confirming? could they not be confirming?
Perfect
could I not have confirmed? could you not have confirmed? could she not have confirmed? could we not have confirmed? could you not have confirmed? could they not have confirmed?
V-ing perfect
could I not have been confirming? could you not have been confirming? could she not have been confirming? could we not have been confirming? could you not have been confirming? could they not have been confirming?