I can ko you can ko he can ko we can ko you can ko they can ko
V-ing form
I can be koing you can be koing he can be koing we can be koing you can be koing they can be koing
Perfect
I can have koed you can have koed he can have koed we can have koed you can have koed they can have koed
V-ing perfect
I can have been koing you can have been koing he can have been koing we can have been koing you can have been koing they can have been koing
Negation
Simple form
I can't ko you can't ko he can't ko we can't ko you can't ko they can't ko
V-ing form
I can't be koing you can't be koing he can't be koing we can't be koing you can't be koing they can't be koing
Perfect
I can't have koed you can't have koed he can't have koed we can't have koed you can't have koed they can't have koed
V-ing perfect
I can't have been koing you can't have been koing he can't have been koing we can't have been koing you can't have been koing they can't have been koing
Interrogative form
Simple form
can I ko? can you ko? can he ko? can we ko? can you ko? can they ko?
V-ing form
can I be koing? can you be koing? can he be koing? can we be koing? can you be koing? can they be koing?
Perfect
can I have koed? can you have koed? can he have koed? can we have koed? can you have koed? can they have koed?
V-ing perfect
can I have been koing? can you have been koing? can he have been koing? can we have been koing? can you have been koing? can they have been koing?
Interro-negative form
Simple form
can't I ko? can't you ko? can't he ko? can't we ko? can't you ko? can't they ko?
V-ing form
can't I be koing? can't you be koing? can't he be koing? can't we be koing? can't you be koing? can't they be koing?
Perfect
can't I have koed? can't you have koed? can't he have koed? can't we have koed? can't you have koed? can't they have koed?
V-ing perfect
can't I have been koing? can't you have been koing? can't he have been koing? can't we have been koing? can't you have been koing? can't they have been koing?