"Is that girl nice?"
Translation:Cette fille est-elle gentille ?
The French often use expressions using different syntax than the classic subject-verb inversion. Sometimes the object is set off with a comma at the beginning or at the end, with a statement after or before it, and a rising inflection at the end to show it is a question. This is common in French as spoken.
Yep, you've written: "the girl, is she nice" and not "that" girl. It's the difference between "la" and "cette". If there were 3 girls standing, and you said, "the girl is she nice", one would have to say, "which girl?", instead of you specifically saying "that girl", so there is difference, although it is subtle.
"Ça" is a demonstrative pronoun; it stands alone referring to another noun. What you need here is a demonstrative adjective: ce, cet, cette. E.g., ce garçon = this/that boy. Cette fille = this/that girl. http://french.about.com/od/grammar/a/adjectives_demonstrative.htm
I think, it would be more appropriate if we used Cette as fille is feminine rather than using Ça. Try this : http://french.about.com/od/grammar/a/adjectives_demonstrative.htm
I think you'll find this useful : http://french.about.com/od/grammar/a/adjectives_demonstrative.htm
It is because the phrasing is not good French at all. The syntax of "Est cette fille sympa" mirrors the syntax of the English "Is that girl nice" but it doesn't work in French. See Sitesurf's examples of different ways to ask questions in French or consult this link: http://french.about.com/od/grammar/a/questions.htm
Yeah, thank you! Sometimes I forget the importance of phraseological aspect, given that some languages are more rigid than others in this regard. I expected somehow that Duolingo would tell me that I have an incorrect wording and (after suggesting me a more natural form) still accept my answer like it does with minor typos.
For your information, the checker here is a computer which compares your suggestion with all correct answers registered in the system for each sentence.
Your proposal is nowhere near any of those, so it is not just a typo but a minimum of 3 words missing: est-ce que cette fille est sympa ?