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 cannot doctor you cannot doctor he cannot doctor we cannot doctor you cannot doctor they cannot doctor
V-ing form
I cannot be doctoring you cannot be doctoring he cannot be doctoring we cannot be doctoring you cannot be doctoring they cannot be doctoring
Perfect
I cannot have doctored you cannot have doctored he cannot have doctored we cannot have doctored you cannot have doctored they cannot have doctored
V-ing perfect
I cannot have been doctoring you cannot have been doctoring he cannot have been doctoring we cannot have been doctoring you cannot have been doctoring they cannot 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 I not doctor? can you not doctor? can he not doctor? can we not doctor? can you not doctor? can they not doctor?
V-ing form
can I not be doctoring? can you not be doctoring? can he not be doctoring? can we not be doctoring? can you not be doctoring? can they not be doctoring?
Perfect
can I not have doctored? can you not have doctored? can he not have doctored? can we not have doctored? can you not have doctored? can they not have doctored?
V-ing perfect
can I not have been doctoring? can you not have been doctoring? can he not have been doctoring? can we not have been doctoring? can you not have been doctoring? can they not have been doctoring?