Translation:Are they Chinese?
English “Are they Chinese?" could be either asking about their nationality or their ethnicity.
If the intention is to focus on the ethnicity, in Chinese it could be rendered as "她们是华人吗？" (华人 huárén)--and which is also a way to refer to Chinese-the-language i.e. "华语" (huáyǔ).
Whenever I'm asked to write what I hear, it seems "他们是中国人吗？" is incorrect. Well, i cannot tell the difference between 他 and 她 if i hear them.
It actually shouldn't because "bu" means no or not. So if i were to add "bu" to the sentence, it would become: tamen bu shi zhongguo ren (are they are NOT chinese?) (also i think that in this situation, duolingo is trying to say [Are they chinese?] instead of [Are they chinese PEOPLE?] because in a lot of other languages on here, people complain about how the translations aren't "modernized" or 'correct'
@Maryam - "all" by itself does not mean plural. It means absolute inclusiveness; every single one in a group being affected by the sentence.
e.g. if I have seven balls, I won't say "I have all of them", but if they were red in colour I'd say "All (seven) of them are red".
Now imagine three of them are green and four are red and if you asked "Are they red?" I'd say "Yes, four of them are red". But if you asked "Are they all red?" I'd say "No. Not all are red, some are green".
Hope you see the difference.
There is a difference to me. "Are they Chinese?" is a pretty neutral question. "They are Chinese?" would likely be stressed more on one of the words, depending on the meaning of the sentence. Reading the second question, I think it is more of a confirmation, either that "they" are the ones we are talking about or that "Chinese" is actually their nationality/ethnicity.
Should be 'aren't they Chinese? rather than Are they Chinese? Aren't they Chinese is emphasising on the question of they are Chinese or not. Where else Are they Chinese, is that you dont know the origin of the people so you ask the question. So the correct reply to the sentence should be Arent they Chinese, as to emphasis on the question in the sentence.