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