I am learning Chinese and here is the English translation on Duolingo. As far as I understand. "has" is right in both cases but Duolingo thinks otherwise.
Is there any other grammar point that I never read or here is a problem in Duolingo?
Why above is wrong and below is right. is it "My Father" will be used as first person singular because of My?
"My father does not has a younger sister" is incorrect. The verb that is used in third person singular here is does, so the verb to have should be used in its root form: "My father does not have a younger sister."
A correct England-English (or old-fashioned USA-English) example of how you could say this with "has" is "My father hasn't a younger sibling." (Hasn't is a contraction for "has" and "not").
You could also say "My father does have a younger sister." You might say that to someone who doubted that your father had a younger sister. You would say "does" with emphasis.
Duolingo is correct. In the first sentence, because "has" is preceded by an auxiliary verb ("does"), it loses its conjugation. In the second, it is conjugated for third person singular because there's no auxiliary.
Auxiliary verbs are typically present in negative statements and questions and may be present in other cases.
