I can teach you can teach he can teach we can teach you can teach they can teach
V-ing form
I can be teaching you can be teaching he can be teaching we can be teaching you can be teaching they can be teaching
Perfect
I can have taught you can have taught he 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 he 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 he 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 he 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 he 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 he 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 he teach? can we teach? can you teach? can they teach?
V-ing form
can I be teaching? can you be teaching? can he be teaching? can we be teaching? can you be teaching? can they be teaching?
Perfect
can I have taught? can you have taught? can he 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 he 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 he 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 he 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 he 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 he have been teaching? can't we have been teaching? can't you have been teaching? can't they have been teaching?