I can down you can down he can down we can down you can down they can down
V-ing form
I can be downing you can be downing he can be downing we can be downing you can be downing they can be downing
Perfect
I can have downed you can have downed he can have downed we can have downed you can have downed they can have downed
V-ing perfect
I can have been downing you can have been downing he can have been downing we can have been downing you can have been downing they can have been downing
Negation
Simple form
I can't down you can't down he can't down we can't down you can't down they can't down
V-ing form
I can't be downing you can't be downing he can't be downing we can't be downing you can't be downing they can't be downing
Perfect
I can't have downed you can't have downed he can't have downed we can't have downed you can't have downed they can't have downed
V-ing perfect
I can't have been downing you can't have been downing he can't have been downing we can't have been downing you can't have been downing they can't have been downing
Interrogative form
Simple form
can I down? can you down? can he down? can we down? can you down? can they down?
V-ing form
can I be downing? can you be downing? can he be downing? can we be downing? can you be downing? can they be downing?
Perfect
can I have downed? can you have downed? can he have downed? can we have downed? can you have downed? can they have downed?
V-ing perfect
can I have been downing? can you have been downing? can he have been downing? can we have been downing? can you have been downing? can they have been downing?
Interro-negative form
Simple form
can't I down? can't you down? can't he down? can't we down? can't you down? can't they down?
V-ing form
can't I be downing? can't you be downing? can't he be downing? can't we be downing? can't you be downing? can't they be downing?
Perfect
can't I have downed? can't you have downed? can't he have downed? can't we have downed? can't you have downed? can't they have downed?
V-ing perfect
can't I have been downing? can't you have been downing? can't he have been downing? can't we have been downing? can't you have been downing? can't they have been downing?