Are you sure???
I've always known "birthday" as "sinh nhật". Is "ngày sinh" a synonym? Or does the former translate directly as "birthday" and the later "birth date"?
No, I set my Facebook birthday a day earlier to weed out my fake friends.
cảm ơn cho thông tin, bây giờ tôi biết.
Dang! i shouldn't log in Duolingo with my google account.
Why is "I know your date of birth" marked incorrect? Birthday and date of birth mean exactly the same thing in English. Also, in other questions in this lesson Duo translates ngày sinh as date of birth.