"There is a pencil inside the box."
Translation:상자 안에는 연필이 있습니다.
This sentence is sort of like saying "As for inside the box, there is a pencil" as opposed to other sentences in this section that are more like "There is a pencil in the box". The 는 marks "In the box" as the subject and focus of the sentence. Perhaps earlier we were talking about what is on top of the box, but now the focus is on what's IN the box. I hope that clarified it and didn't make it more confusing!
It's like saying "As for the inside of the box, blah blah.." You could say it like that if you were telling someone to find the box and then get something out of the box I suppose. 내 피아노 위에 상자가 보이지..그래, 상자 안에는 연필이 있어, 가져와줄래?
And for the record, 은/는 is a topic particle, not a subject particle. Topic particles can be used for a wider variety of cases than just subjects.
I "kinda" understand the point you guys are making on this sentence and the word the particle is attached to. But the sentence 연필이 상자 안에 있어요 should also be accepted, right?
As there is no context to be based on, we are left with the sentence as it is. We cannot know for sure where is the emphases.
By the way... I wish there was a way we could see all the accepted answers in a particular exercise.
Okay but why is it the only sentence of that type where the 은/는 is used (in this duolingo practice of course ) ? Is it wrong not to use it ?
안 is connected to 상자 so it means 'the inside of the box', which is a noun and needs a subject marker.
Hi Aira, sorry, but you may be under a misimpression. A "noun" doesn't require a "subject marker" ( 이/가) unless it is functioning as the subject of the sentence. You won't find any nouns in the language followed by both a location and a subject or topic marker. Both Winter and Nick seem to be quite knowledgable in Korean (I believe Nick still lives there) so, their posts are pretty reliable.
Check out the other answers in this thread, it's covered at different levels of detail.
연필이 상자 안에 있습니다 would still be grammatically right , isn't it? It would not focus on the box, but still be right?