Translation:Does she have an older sister?
Your answer was incorrect because 姐姐 means 'older sister,' not simply 'sister'. In Chinese, older/younger is usually differentiated when referring to relatives. For example, older brother (哥哥) and younger brother (弟弟), older female cousin (表姐) and younger female cousin (表妹), so on.
I guess if there were no words written, DL would’ve considered《他/她》as any of the two genders, but《她》was specifically written in the example, so I suppose you have to follow what the example directly asks for which is the “she” one.
No. For some reasons single character words are less popular in modern Chinese. Words have been formed by using 2 characters of the same meaning such as 朋友 friend. Each of 朋 and 友 alone can mean friend in older time. 姐姐 is just an example of doubling the same character. It does not carry any implication of single or plural.
I don't completely understand your question, but I'll try to help anyway :P
There is no plural form for words in Chinese, but you can specify amounts of things.
If you said ”她有一个姐姐吗？“ that would mean "Does she have one older sister?" or "Does she have an older sister?".
If you said "她有三个姐姐吗？" that would mean "Does she have three older sisters?".
And if you said "她有多个姐姐吗？" that would mean "Does she have multiple older sisters?".
I hope this answers your question, and let me know if there is anything else that's not clear :)
I am a native English speaker from the UK - 'Has she an older sister?' is correct but it is very unusual in modern times. Almost everyone would say 'Does she have an older sister?'. You are more likely to read or hear 'Has she an older sister?' in a Shakespeare play :)
(As @EthanKamin mentioned, you could hear an older Irish or Scottish person using either sentence. As far as people from England go, I think 'Has she an older sister?' is unusual no matter what).
It is a question about English. I am not native but I came across such discussion between natives. It seems that the form "Has she xxxx?" is not very popular, both in UK and in US. However I doubt if anyone would regard it as "wrong", just hardly people talk like that. Maybe someone native could comment about this to confirm.
In my native dialect (US west coast, born '80s/'90s), "has she an..." is definitely ungrammatical/not used. For me, a sentence starting with "has she..." would have to be followed by a verb - the "already did something" meaning of "has", not the "possesses/exists" meaning. So yes, in my dialect, it's definitely "wrong" (I'd give someone a really weird look if they said "Has she hella sick rims?", for instance, and not because of the "hella sick" colloquialism or because of a formal/informal mixup).
Other dialects out there do use "Has she..." to mean "Does she have [possess/etc.]...", and I think that construction might be encountered more frequently in Britain. (I've heard it from some older Irish speakers, for instance)
@tu - It's great that you managed to learn English which also has words with many meanings. e.g. You put 'up' with things that get brought 'up' in discussions and then sum it 'up' in the end. Whilst none of these are actually going 'up' from a direction perspective. :-)
Uniza and Patrick - As Patrick says where you use do/ does to create a question, the main verb changes back to the infinitive form without the 'to' as Doctor Who 01 explains nicely below. However, my point was a much simpler one. Although the most common use of inversion of verb and noun/ pronoun to make a question is with the verb to be, you can (usually for stylistic reasons) do the same where the verb is to have. In those cases, the verb retains the original format. Have I? Have you? Has he/she/ it? Duolingo, however, did not recognise that option in this particular example. But I am just being pedantic.
In English in interrogative sentences (i. e. in questions) you usually use auxillary verbs that are conjucated, and the main verb is just a bare infinitive (i. e. without 'to'), so let's take the verb "to take"
Affirmative present simple:
I take a look. She takes a look.
Interrogative present simple:
Do I take a look. DOES she take (no 's') a look.
Affirmative past simple:
I took a look. She took a look.
Interrogative present simple:
DID I take a look. DID she take a look.