"My younger sisters are in front of and behind me."
I'm not anything close to fluent in Japanese, but I'll try to give a more helpful answer.
は here is doing basically the same thing as when it replaces が; a phrase is marked as a topic, rather than taking its usual place in the syntax of the sentence. When that's a subject or a direct object, you lose the が or を, but something like に is kept before the は. So 「前と後ろにはいもうとたちがいます。」 is literally something like "As for in front of and behind me, there's my little sisters." One could instead topicalize the sisters: 「いもうとたちは前と後ろにいます。」 "As for my little sisters, they're in front of and behind me." These different versions of the sentence might perhaps answer the questions "Who is near you?" and "Where are your siblings?" respectively.
[mae to ushiro ni] is the main focus of that sentence. The whole sentence is literally saying something like "As for what's in my front and back, it's my sisters". Except obviously, you don't translate it into something stupid like that, instead you translate it into something that makes sense in English.
It's not always necessary to indicate plurality in Japanese.
If you think about it, why do we (in English and other languages) distinguish between one and two, but not two and three (or any other number)? As native Japanese speaker sora_Japan pointed out in another thread, two is closer to one than it is to a billion.
Just food for thought!
I don't think it should be necessarily wrong, because, languages like Japanese (that used particles or heavy forms of inflection (like Russian in the latter)), the clauses can have different ordering without altering the general sense of the sentence (except verbs, they tend to go at the end of a sentence/clause), but they tend to put some terms first instead of others (i.e. time phrases before anything else).
Well now, the English sentence translates differently, and so does the japanese sentence.
Duolingo says: my younger sisters are in front and behind me. Literal translation is: 私の妹は私の前と後ろにいます Watashi no imōto wa watashi no mae to ushiro ni imasu.
Duolingo answer is: 前と後ろには妹たちがいます Mae to ushironi wa imōto-tachi ga imasu Literal translation: there are sisters in front and behind.
This is what makes Japanese confusing. And why my Japanese friends do not understand what they are reading.
The subject in this case is the location; if the sisters were the subject, the pharse would be "妹たちは前と後ろにいます。"; the focus on the subject may differ from a language to another, with Japanese talking first about time and location; both subjects would be fine in English just given their corresponding contexts.
"No" is usually used as an indication of possession, while "ni" is used indicating location. What you probably refer to is the "...の前と後ろに..." structure, right? (Somebody)の(前と後ろ)に(Verb) This means, (Somebody)(Has)(The front and back)(At)(Verb). It's quite tricky to translate to English, becouse in English we use ""I am at your back", while Japanese uses the "I have your back" structure. As far as I know.
Uh, I'm not completely sure why you thought that would work. You said: たくさん (a lot of) • 妹 (younger sister) • が (subject marker) • あります (to exist). So you said "A lot of younger sisters exist." Not only that, you used あります which is for nonliving objects rather than います for living or once living. Last time I checked, younger sisters are living beings.
Now, here's the correct solution duo presents. [There is first an omitted/ uneeded with context 私の meaning "my"] •前 (front) • と (and) • 後ろ (behind) • には (location + topic marker) • 妹たち (younger sisters) • が (subject marker) • います (to exist for LIVING objects). So literally, this means, "In front and behind (of me), younger sisters are existing.
If you still have any further questions as to why this is the correct solution or just something else, feel free to ask!
I can't assure 100% if it is grammatically wrong but it definitely doesn't sound natural. The は particle marks the topic of the sentence, so everything that comes after it is related to what comes before it. In your example the whole sentence except the verb is marked by は.
If only 妹たち was marked with は then it would be "as for my younger sisters, they are in front of and behind me"
If only 前と後ろに was marked with は then it would be "as for in front of and behind me, my younger sisters exist"
Marking 妹たちが前と後ろに with は it would be something like "as for my younger sister in front of and behind me, they exist" (no reason for this は particle)
Both are right and depends on the situation and context that you are in. For exemple, using が with the sisters, you are making them the subject of the verb いる (which is the case here). If you mark them with は, then they would be the topic of the sentence.
In this case what is marked with は is "in front and behind me", so that is the topic. You are making a statement about "in front and behind me":
前と後ろには妹たちがにいます。 = About "in front and behind me", my younger sisters exists.
If you use は with the sisters then now they are the topic.
妹たちは前と後ろにいます。About my younger sisters, they are in front and behind me.
前 you can remember this kanji by two arms reaching out of desire with a line under, below that is the moon radical and to the right of it is リ in katakana, kf anyone could make a story about the components that relate to rhe meaning or pronouciation of まえ前 it would be even easier to remember next is 後ろ it consists of 彳幺夊 And いもうと妹女未
i can't get a grip of the sentence structure in this lesson section.. it seemed to me that when talking about position with an object, position goes first. but with the position of a person, the person goes first. but clearly i'm wrong. can someone help clear this up for me?