I can down you can down she can down we can down you can down they can down
V-ing form
I can be downing you can be downing she can be downing we can be downing you can be downing they can be downing
Perfect
I can have downed you can have downed she 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 she 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 she 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 she 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 she 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 she 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 she down? can we down? can you down? can they down?
V-ing form
can I be downing? can you be downing? can she be downing? can we be downing? can you be downing? can they be downing?
Perfect
can I have downed? can you have downed? can she 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 she 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 she 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 she 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 she 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 she have been downing? can't we have been downing? can't you have been downing? can't they have been downing?