I can rat you can rat he can rat we can rat you can rat they can rat
V-ing form
I can be ratting you can be ratting he can be ratting we can be ratting you can be ratting they can be ratting
Perfect
I can have ratted you can have ratted he can have ratted we can have ratted you can have ratted they can have ratted
V-ing perfect
I can have been ratting you can have been ratting he can have been ratting we can have been ratting you can have been ratting they can have been ratting
Negation
Simple form
I can't rat you can't rat he can't rat we can't rat you can't rat they can't rat
V-ing form
I can't be ratting you can't be ratting he can't be ratting we can't be ratting you can't be ratting they can't be ratting
Perfect
I can't have ratted you can't have ratted he can't have ratted we can't have ratted you can't have ratted they can't have ratted
V-ing perfect
I can't have been ratting you can't have been ratting he can't have been ratting we can't have been ratting you can't have been ratting they can't have been ratting
Interrogative form
Simple form
can I rat? can you rat? can he rat? can we rat? can you rat? can they rat?
V-ing form
can I be ratting? can you be ratting? can he be ratting? can we be ratting? can you be ratting? can they be ratting?
Perfect
can I have ratted? can you have ratted? can he have ratted? can we have ratted? can you have ratted? can they have ratted?
V-ing perfect
can I have been ratting? can you have been ratting? can he have been ratting? can we have been ratting? can you have been ratting? can they have been ratting?
Interro-negative form
Simple form
can't I rat? can't you rat? can't he rat? can't we rat? can't you rat? can't they rat?
V-ing form
can't I be ratting? can't you be ratting? can't he be ratting? can't we be ratting? can't you be ratting? can't they be ratting?
Perfect
can't I have ratted? can't you have ratted? can't he have ratted? can't we have ratted? can't you have ratted? can't they have ratted?
V-ing perfect
can't I have been ratting? can't you have been ratting? can't he have been ratting? can't we have been ratting? can't you have been ratting? can't they have been ratting?