I can curb you can curb he can curb we can curb you can curb they can curb
V-ing form
I can be curbing you can be curbing he can be curbing we can be curbing you can be curbing they can be curbing
Perfect
I can have curbed you can have curbed he can have curbed we can have curbed you can have curbed they can have curbed
V-ing perfect
I can have been curbing you can have been curbing he can have been curbing we can have been curbing you can have been curbing they can have been curbing
Negation
Simple form
I can't curb you can't curb he can't curb we can't curb you can't curb they can't curb
V-ing form
I can't be curbing you can't be curbing he can't be curbing we can't be curbing you can't be curbing they can't be curbing
Perfect
I can't have curbed you can't have curbed he can't have curbed we can't have curbed you can't have curbed they can't have curbed
V-ing perfect
I can't have been curbing you can't have been curbing he can't have been curbing we can't have been curbing you can't have been curbing they can't have been curbing
Interrogative form
Simple form
can I curb? can you curb? can he curb? can we curb? can you curb? can they curb?
V-ing form
can I be curbing? can you be curbing? can he be curbing? can we be curbing? can you be curbing? can they be curbing?
Perfect
can I have curbed? can you have curbed? can he have curbed? can we have curbed? can you have curbed? can they have curbed?
V-ing perfect
can I have been curbing? can you have been curbing? can he have been curbing? can we have been curbing? can you have been curbing? can they have been curbing?
Interro-negative form
Simple form
can't I curb? can't you curb? can't he curb? can't we curb? can't you curb? can't they curb?
V-ing form
can't I be curbing? can't you be curbing? can't he be curbing? can't we be curbing? can't you be curbing? can't they be curbing?
Perfect
can't I have curbed? can't you have curbed? can't he have curbed? can't we have curbed? can't you have curbed? can't they have curbed?
V-ing perfect
can't I have been curbing? can't you have been curbing? can't he have been curbing? can't we have been curbing? can't you have been curbing? can't they have been curbing?