I can teach you can teach she can teach we can teach you can teach they can teach
V-ing form
I can be teaching you can be teaching she can be teaching we can be teaching you can be teaching they can be teaching
Perfect
I can have taught you can have taught she can have taught we can have taught you can have taught they can have taught
V-ing perfect
I can have been teaching you can have been teaching she can have been teaching we can have been teaching you can have been teaching they can have been teaching
Negation
Simple form
I can't teach you can't teach she can't teach we can't teach you can't teach they can't teach
V-ing form
I can't be teaching you can't be teaching she can't be teaching we can't be teaching you can't be teaching they can't be teaching
Perfect
I can't have taught you can't have taught she can't have taught we can't have taught you can't have taught they can't have taught
V-ing perfect
I can't have been teaching you can't have been teaching she can't have been teaching we can't have been teaching you can't have been teaching they can't have been teaching
Interrogative form
Simple form
can I teach? can you teach? can she teach? can we teach? can you teach? can they teach?
V-ing form
can I be teaching? can you be teaching? can she be teaching? can we be teaching? can you be teaching? can they be teaching?
Perfect
can I have taught? can you have taught? can she have taught? can we have taught? can you have taught? can they have taught?
V-ing perfect
can I have been teaching? can you have been teaching? can she have been teaching? can we have been teaching? can you have been teaching? can they have been teaching?
Interro-negative form
Simple form
can't I teach? can't you teach? can't she teach? can't we teach? can't you teach? can't they teach?
V-ing form
can't I be teaching? can't you be teaching? can't she be teaching? can't we be teaching? can't you be teaching? can't they be teaching?
Perfect
can't I have taught? can't you have taught? can't she have taught? can't we have taught? can't you have taught? can't they have taught?
V-ing perfect
can't I have been teaching? can't you have been teaching? can't she have been teaching? can't we have been teaching? can't you have been teaching? can't they have been teaching?