I can walk you can walk she can walk we can walk you can walk they can walk
V-ing form
I can be walking you can be walking she can be walking we can be walking you can be walking they can be walking
Perfect
I can have walked you can have walked she can have walked we can have walked you can have walked they can have walked
V-ing perfect
I can have been walking you can have been walking she can have been walking we can have been walking you can have been walking they can have been walking
Negation
Simple form
I can't walk you can't walk she can't walk we can't walk you can't walk they can't walk
V-ing form
I can't be walking you can't be walking she can't be walking we can't be walking you can't be walking they can't be walking
Perfect
I can't have walked you can't have walked she can't have walked we can't have walked you can't have walked they can't have walked
V-ing perfect
I can't have been walking you can't have been walking she can't have been walking we can't have been walking you can't have been walking they can't have been walking
Interrogative form
Simple form
can I walk? can you walk? can she walk? can we walk? can you walk? can they walk?
V-ing form
can I be walking? can you be walking? can she be walking? can we be walking? can you be walking? can they be walking?
Perfect
can I have walked? can you have walked? can she have walked? can we have walked? can you have walked? can they have walked?
V-ing perfect
can I have been walking? can you have been walking? can she have been walking? can we have been walking? can you have been walking? can they have been walking?
Interro-negative form
Simple form
can't I walk? can't you walk? can't she walk? can't we walk? can't you walk? can't they walk?
V-ing form
can't I be walking? can't you be walking? can't she be walking? can't we be walking? can't you be walking? can't they be walking?
Perfect
can't I have walked? can't you have walked? can't she have walked? can't we have walked? can't you have walked? can't they have walked?
V-ing perfect
can't I have been walking? can't you have been walking? can't she have been walking? can't we have been walking? can't you have been walking? can't they have been walking?