"There is a chair behind me."
Sometimes I remember what a certain Kanji means, but not how it is pronounced (this was the case with 後) what advice do you have for these cases?
I recommend using a second app to look up the pronounciation. I use Kanji Study on android myself. Jisho might work great as well.
I heard reading books have oniyomi and kunyomi. Maybe some reading books might help. Libraries can have books for other languages especially university libraries if you're allowed in them.
Am I to understand that if an object is omitted, by default the object is understood to be me? ( Ehy not "you"?) Or is this just duolingo deciding that imaginary context would make it so?
You understand correctly. Japanese prefer not to expressly state subjects. This is not a duolingo problem. This is the way Japanese people communicate. They infer context all the time when they think it's obvious or that people can figure it out without them spelling it out.
I have lived with my Japanese husband who speaks English well, and still there are times that I get an indefinite answer from him or NO answer. lol So even though we communicate in English, he still has the Japanese style of indirectness.
it's both. Omitting the subjrct or topic is extremely common in japanese, whenever the context is clear enough. Duo tries to use the language as it would be used, so they omit topics frequently, and use "me" as an imaginary context so that there aren't 50+ right answers to every question.
If I wanted to write the full scentence, where did I have to put the 私? In front of the 後ろ?
That is correct, you would then use a の particle afterwards. So it would be 私の後ろ...
why can't you do it the other way around, like いすがわたしの後ろにあります/the chair there is one behind me?
Furthermore, in this case, there is an implicit subject (the speaker), so you could think of it as 「[僕の]後ろにいすがあります」. You are describing the object (a chair) in relation to the subject (the speaker). I think 「が」 is primarily used to describe the object, so you use 「が」 even when the subject is elided.
I think it's also because it is an exclusive description: i.e, the chair is not anywhere else but behind you: 後ろにあります. I think the English sentence in this example is a bit confusing because it is a more general statement that "there is a chair behind me" rather than "the chair is behind me", which seems like what the Japanese sentence is actually saying.
You would use は for inclusive descriptions, i.e. if you say that you're a member of the NRA, that doesn't mean you're not a member of some other charitable organization, therefore 「[SUBJECT]は[OBJECT]の会員です」. By that same token, even if a description is not generally exclusive, in some cases it can warrant a 「が」, and that can also come along with dropping some particles like 「の」in certain cases, it's tricky.
There are other subtle signals sent by the choice between 「は」 and 「が」, and you're honestly more likely to figure them out with listening experience than with hard and fast rules.
I entered いすが後ろにあります and it was accepted. Is the word order not important then? What is the difference between the two, if any?
the word order isn't very important here. Because of the use of particles (が and に in this sentence) to mark the grammatical function of words, it's understandable in almost any order, so long as the particles are paired up right. Order can change the emphasis of a sentence too.
うしろ - physically behind something (location)
あと - 1) after (time), 2) physically behind something (location)
They can sometimes be interchangeable.
Other translations are possible, but "there is a chair behind" is an incomplete sentence in English, so we have to make a reasonable assumption about what it is behind. It's behind something, and if I'm the person speaking, it's most likely behind me
When using います and あります to mean that something exists, います is used for animate objects and あります is used for inanimate objects. A chair is inanimate, so we use あります.
Just so I understand how I got this wrong:
後ろに椅子があります。 means "There is a chair behind me."
椅子の後ろにあります。means "I am behind the chair."
Am I understanding my mistake correctly?
You've got the main idea, but there's one more element to it. あります (arimasu) can only be used with inanimate objects, so your second sentence means "(something) is behind the chair". If you want to say that you, a living person, are behind a chair, you need to replace あります with います (imasu).
I asked my japanese teacher once, if plants are inanime (ある) or animate (いる). She wasn't sure, but said first inanimate. Later she discussed it with friends and told me they also thought of plants as inanimate.
why do I hear "the chair in behind it is, a way the Japanese their language to understand that is" echo in Master Yoda's voice?
It told me the answer was いすが後ろにある, but it didn't have an option to select ある so I put, いすが後ろにます which it marked as wrong.
I've reported it but as it won't give me the option for the answer it says is correct. can someone tell me what's wrong with the answer I gave?
ます (masu) is just the ending of a verb, it's not actually a word, so you needed the stem of the verb to complete your answer.
The answer that it tells you is "right" is the version of the answer that you came closest to (there is more than one right answer). The preferred answer at the top of this thread is 後にいすがあります (ushiro ni isu ga arimasu). ある (aru) is the short form of あります (arimasu). I'm guessing there was probably a floating あり (ari) somewhere in your options.