I could see you could see she could see we could see you could see they could see
V-ing form
I could be seeing you could be seeing she could be seeing we could be seeing you could be seeing they could be seeing
Perfect
I could have seen you could have seen she could have seen we could have seen you could have seen they could have seen
V-ing perfect
I could have been seeing you could have been seeing she could have been seeing we could have been seeing you could have been seeing they could have been seeing
Negation
Simple form
I could not see you could not see she could not see we could not see you could not see they could not see
V-ing form
I could not be seeing you could not be seeing she could not be seeing we could not be seeing you could not be seeing they could not be seeing
Perfect
I could not have seen you could not have seen she could not have seen we could not have seen you could not have seen they could not have seen
V-ing perfect
I could not have been seeing you could not have been seeing she could not have been seeing we could not have been seeing you could not have been seeing they could not have been seeing
Interrogative form
Simple form
could I see? could you see? could she see? could we see? could you see? could they see?
V-ing form
could I be seeing? could you be seeing? could she be seeing? could we be seeing? could you be seeing? could they be seeing?
Perfect
could I have seen? could you have seen? could she have seen? could we have seen? could you have seen? could they have seen?
V-ing perfect
could I have been seeing? could you have been seeing? could she have been seeing? could we have been seeing? could you have been seeing? could they have been seeing?
Interro-negative form
Simple form
could I not see? could you not see? could she not see? could we not see? could you not see? could they not see?
V-ing form
could I not be seeing? could you not be seeing? could she not be seeing? could we not be seeing? could you not be seeing? could they not be seeing?
Perfect
could I not have seen? could you not have seen? could she not have seen? could we not have seen? could you not have seen? could they not have seen?
V-ing perfect
could I not have been seeing? could you not have been seeing? could she not have been seeing? could we not have been seeing? could you not have been seeing? could they not have been seeing?