sentences:  In sentence number 2, the doctor is a woman, so the noun is referred back with a feminine pronoun.But in sentence number 3, even though I know if the doctor is a man or a woman, it is perfectly possible to still dodge the definition by using the always available gender-neutral pronoun lu.Notice however that doktoro is never marked for gender in these sentences, since the doctor will be called in his/her professional capacity, and not for being a man or a woman.