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 can't compare you can't compare she can't compare we can't compare you can't compare they can't compare
V-ing form
I can't be comparing you can't be comparing she can't be comparing we can't be comparing you can't be comparing they can't be comparing
Perfect
I can't have compared you can't have compared she can't have compared we can't have compared you can't have compared they can't have compared
V-ing perfect
I can't have been comparing you can't have been comparing she can't have been comparing we can't have been comparing you can't have been comparing they can't 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't I compare? can't you compare? can't she compare? can't we compare? can't you compare? can't they compare?
V-ing form
can't I be comparing? can't you be comparing? can't she be comparing? can't we be comparing? can't you be comparing? can't they be comparing?
Perfect
can't I have compared? can't you have compared? can't she have compared? can't we have compared? can't you have compared? can't they have compared?
V-ing perfect
can't I have been comparing? can't you have been comparing? can't she have been comparing? can't we have been comparing? can't you have been comparing? can't they have been comparing?