I can rub you can rub he can rub we can rub you can rub they can rub
V-ing form
I can be rubbing you can be rubbing he can be rubbing we can be rubbing you can be rubbing they can be rubbing
Perfect
I can have rubbed you can have rubbed he can have rubbed we can have rubbed you can have rubbed they can have rubbed
V-ing perfect
I can have been rubbing you can have been rubbing he can have been rubbing we can have been rubbing you can have been rubbing they can have been rubbing
Negation
Simple form
I can't rub you can't rub he can't rub we can't rub you can't rub they can't rub
V-ing form
I can't be rubbing you can't be rubbing he can't be rubbing we can't be rubbing you can't be rubbing they can't be rubbing
Perfect
I can't have rubbed you can't have rubbed he can't have rubbed we can't have rubbed you can't have rubbed they can't have rubbed
V-ing perfect
I can't have been rubbing you can't have been rubbing he can't have been rubbing we can't have been rubbing you can't have been rubbing they can't have been rubbing
Interrogative form
Simple form
can I rub? can you rub? can he rub? can we rub? can you rub? can they rub?
V-ing form
can I be rubbing? can you be rubbing? can he be rubbing? can we be rubbing? can you be rubbing? can they be rubbing?
Perfect
can I have rubbed? can you have rubbed? can he have rubbed? can we have rubbed? can you have rubbed? can they have rubbed?
V-ing perfect
can I have been rubbing? can you have been rubbing? can he have been rubbing? can we have been rubbing? can you have been rubbing? can they have been rubbing?
Interro-negative form
Simple form
can't I rub? can't you rub? can't he rub? can't we rub? can't you rub? can't they rub?
V-ing form
can't I be rubbing? can't you be rubbing? can't he be rubbing? can't we be rubbing? can't you be rubbing? can't they be rubbing?
Perfect
can't I have rubbed? can't you have rubbed? can't he have rubbed? can't we have rubbed? can't you have rubbed? can't they have rubbed?
V-ing perfect
can't I have been rubbing? can't you have been rubbing? can't he have been rubbing? can't we have been rubbing? can't you have been rubbing? can't they have been rubbing?