I can doctor you can doctor he can doctor we can doctor you can doctor they can doctor
V-ing form
I can be doctoring you can be doctoring he can be doctoring we can be doctoring you can be doctoring they can be doctoring
Perfect
I can have doctored you can have doctored he can have doctored we can have doctored you can have doctored they can have doctored
V-ing perfect
I can have been doctoring you can have been doctoring he can have been doctoring we can have been doctoring you can have been doctoring they can have been doctoring
Negation
Simple form
I can't doctor you can't doctor he can't doctor we can't doctor you can't doctor they can't doctor
V-ing form
I can't be doctoring you can't be doctoring he can't be doctoring we can't be doctoring you can't be doctoring they can't be doctoring
Perfect
I can't have doctored you can't have doctored he can't have doctored we can't have doctored you can't have doctored they can't have doctored
V-ing perfect
I can't have been doctoring you can't have been doctoring he can't have been doctoring we can't have been doctoring you can't have been doctoring they can't have been doctoring
Interrogative form
Simple form
can I doctor? can you doctor? can he doctor? can we doctor? can you doctor? can they doctor?
V-ing form
can I be doctoring? can you be doctoring? can he be doctoring? can we be doctoring? can you be doctoring? can they be doctoring?
Perfect
can I have doctored? can you have doctored? can he have doctored? can we have doctored? can you have doctored? can they have doctored?
V-ing perfect
can I have been doctoring? can you have been doctoring? can he have been doctoring? can we have been doctoring? can you have been doctoring? can they have been doctoring?
Interro-negative form
Simple form
can't I doctor? can't you doctor? can't he doctor? can't we doctor? can't you doctor? can't they doctor?
V-ing form
can't I be doctoring? can't you be doctoring? can't he be doctoring? can't we be doctoring? can't you be doctoring? can't they be doctoring?
Perfect
can't I have doctored? can't you have doctored? can't he have doctored? can't we have doctored? can't you have doctored? can't they have doctored?
V-ing perfect
can't I have been doctoring? can't you have been doctoring? can't he have been doctoring? can't we have been doctoring? can't you have been doctoring? can't they have been doctoring?