I can caution you can caution he can caution we can caution you can caution they can caution
V-ing form
I can be cautioning you can be cautioning he can be cautioning we can be cautioning you can be cautioning they can be cautioning
Perfect
I can have cautioned you can have cautioned he can have cautioned we can have cautioned you can have cautioned they can have cautioned
V-ing perfect
I can have been cautioning you can have been cautioning he can have been cautioning we can have been cautioning you can have been cautioning they can have been cautioning
Negation
Simple form
I can't caution you can't caution he can't caution we can't caution you can't caution they can't caution
V-ing form
I can't be cautioning you can't be cautioning he can't be cautioning we can't be cautioning you can't be cautioning they can't be cautioning
Perfect
I can't have cautioned you can't have cautioned he can't have cautioned we can't have cautioned you can't have cautioned they can't have cautioned
V-ing perfect
I can't have been cautioning you can't have been cautioning he can't have been cautioning we can't have been cautioning you can't have been cautioning they can't have been cautioning
Interrogative form
Simple form
can I caution? can you caution? can he caution? can we caution? can you caution? can they caution?
V-ing form
can I be cautioning? can you be cautioning? can he be cautioning? can we be cautioning? can you be cautioning? can they be cautioning?
Perfect
can I have cautioned? can you have cautioned? can he have cautioned? can we have cautioned? can you have cautioned? can they have cautioned?
V-ing perfect
can I have been cautioning? can you have been cautioning? can he have been cautioning? can we have been cautioning? can you have been cautioning? can they have been cautioning?
Interro-negative form
Simple form
can't I caution? can't you caution? can't he caution? can't we caution? can't you caution? can't they caution?
V-ing form
can't I be cautioning? can't you be cautioning? can't he be cautioning? can't we be cautioning? can't you be cautioning? can't they be cautioning?
Perfect
can't I have cautioned? can't you have cautioned? can't he have cautioned? can't we have cautioned? can't you have cautioned? can't they have cautioned?
V-ing perfect
can't I have been cautioning? can't you have been cautioning? can't he have been cautioning? can't we have been cautioning? can't you have been cautioning? can't they have been cautioning?