I could compare you could compare she could compare we could compare you could compare they could compare
V-ing form
I could be comparing you could be comparing she could be comparing we could be comparing you could be comparing they could be comparing
Perfect
I could have compared you could have compared she could have compared we could have compared you could have compared they could have compared
V-ing perfect
I could have been comparing you could have been comparing she could have been comparing we could have been comparing you could have been comparing they could have been comparing
Negation
Simple form
I could not compare you could not compare she could not compare we could not compare you could not compare they could not compare
V-ing form
I could not be comparing you could not be comparing she could not be comparing we could not be comparing you could not be comparing they could not be comparing
Perfect
I could not have compared you could not have compared she could not have compared we could not have compared you could not have compared they could not have compared
V-ing perfect
I could not have been comparing you could not have been comparing she could not have been comparing we could not have been comparing you could not have been comparing they could not have been comparing
Interrogative form
Simple form
could I compare? could you compare? could she compare? could we compare? could you compare? could they compare?
V-ing form
could I be comparing? could you be comparing? could she be comparing? could we be comparing? could you be comparing? could they be comparing?
Perfect
could I have compared? could you have compared? could she have compared? could we have compared? could you have compared? could they have compared?
V-ing perfect
could I have been comparing? could you have been comparing? could she have been comparing? could we have been comparing? could you have been comparing? could they have been comparing?
Interro-negative form
Simple form
could I not compare? could you not compare? could she not compare? could we not compare? could you not compare? could they not compare?
V-ing form
could I not be comparing? could you not be comparing? could she not be comparing? could we not be comparing? could you not be comparing? could they not be comparing?
Perfect
could I not have compared? could you not have compared? could she not have compared? could we not have compared? could you not have compared? could they not have compared?
V-ing perfect
could I not have been comparing? could you not have been comparing? could she not have been comparing? could we not have been comparing? could you not have been comparing? could they not have been comparing?