I can ko you can ko she can ko we can ko you can ko they can ko
V-ing form
I can be koing you can be koing she can be koing we can be koing you can be koing they can be koing
Perfect
I can have koed you can have koed she 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 she can have been koing we can have been koing you can have been koing they can have been koing
Negation
Simple form
I cannot ko you cannot ko she cannot ko we cannot ko you cannot ko they cannot ko
V-ing form
I cannot be koing you cannot be koing she cannot be koing we cannot be koing you cannot be koing they cannot be koing
Perfect
I cannot have koed you cannot have koed she cannot have koed we cannot have koed you cannot have koed they cannot have koed
V-ing perfect
I cannot have been koing you cannot have been koing she cannot have been koing we cannot have been koing you cannot have been koing they cannot have been koing
Interrogative form
Simple form
can I ko? can you ko? can she ko? can we ko? can you ko? can they ko?
V-ing form
can I be koing? can you be koing? can she be koing? can we be koing? can you be koing? can they be koing?
Perfect
can I have koed? can you have koed? can she 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 she have been koing? can we have been koing? can you have been koing? can they have been koing?
Interro-negative form
Simple form
can I not ko? can you not ko? can she not ko? can we not ko? can you not ko? can they not ko?
V-ing form
can I not be koing? can you not be koing? can she not be koing? can we not be koing? can you not be koing? can they not be koing?
Perfect
can I not have koed? can you not have koed? can she not have koed? can we not have koed? can you not have koed? can they not have koed?
V-ing perfect
can I not have been koing? can you not have been koing? can she not have been koing? can we not have been koing? can you not have been koing? can they not have been koing?