"Are you a foreign exchange student?"
Why Duolingo don't use the kanji for 学生? We have learned that
We didn't learn 留 though and its all one word. Rather than have the word split between kanji and hiragana its all kept as hiragana. That's my guess.
Nice idea, but they give us りゅうがく生 which is still a mix of hiragana and kanji :/
I think their rationale is to not split up 留学 which is a stand-alone word for "studying abroad". You could argue that 学生 is a stand-alone word too, and it is, but it's much more common to add 生 to the end of other words (such as 一年生 ichi nen sei = "first year student", or 高校生 kou kou sei = "high school student") than it is to add 留 to the start of other words (and have it retain a similar meaning).
Actually a lot of small children do! ... Okay that rather proves your point, now doens't it?
Why no 'wa' or 'ni' (I temporarily forget which) to indicate the subject of the sentence?
に is for places so... That ones out. The は is silent because it was cut out. Unimportant parts are often omitted. You 'could' extend the sentence to be あなたはりゅう学生ですか? but why would you when whoever youre talking to obviously knows youre asking them. Its like in english i can ask "are you a foreign student?" Or i can make eye contact and ask "foreign student?"
Exactly! Three small addition, though...
- は marks the topic of the conversation, so it marks the topic of this sentence as well as every other sentence after it until someone sets は again, so if someone introduces themselves with 「わたしは フォンジ です」, then someone can ask me 「りゅうがくせい だか？」 using my earlier わたしは since it's still intact.
- Asking "Foreign student?" is incorrect grammar in English, though asking 「りゅうがくせい だか」 is grammatically correct in Japanese, as long as the conversational topic has already been established.
- Then again, walking up to someone going 「フォンジ です」 kind of already marks myself as the topic socially, since it really is that obvious, I wouldn't walk up to someone and tell them "Hi, you're Fonzie now, good luck with that!"
Actually, "Foreign student?" is a perfectly grammatical English question. There's a lot of nonsense sometimes taught in school about English, much of it having to do with attempts to shoe-horn rules from "Classical" languages into English.
Japanese tends to leave out the subject if they think it is obvious. If i am asking you a question then yoi can assume I am talking about you unless we have already mentioned someone else.