confused with words of duratin and such

[Chronitsch]

Hi there

Again I have a question

our homework is today about まで、　までに、間、間に、うちに

with 間、間に i hav less problems, the first is a duration and the second is a fixed point of time (i think)

with まで、までに i have slight problems. while i know the latter means until a fixed time and not longer (like a deadline) i dont exactly know the usage of まで. I do kno the usage when you say from 9 o'clock to 12 o clock but are there other usages?

and with うちに i a completly lost, i think it means something like "before" like
ザルツブルグに帰るうちにウイーンでいいプルゼントを買いたい。would mean
Before I go to Salzburg I want to buy good presents in Vienna. but i am not completely sure if there are other more common usages.

and another question, a sentence i dont get at all and thus dont know what word to use is the following.
両親が帰って来ない＿＿＿＿＿＿そうじをしいなければなりません。

Does the first part mean Before my parenst dont return?
I think the second part means I wont be able to tidy up, and thus it would be either うちに or まで
Please help me out ._.

[trykyn]

まで　and までに　basically mean the same thing, "until", while までに gives the impression of a sharper deadline.
In english you might think of them as "until..." and "until ... sharp"

for uchi, if you'd write it in kanji (altohugh normally written in hiragana only) it becomes 内, maybe helping with the meaning
kind of means within, or while

so your sentence would mean: within (the time to) return to salzburg, i want to buy a nice present in wien

for your quiz sentence, i am not sure if an い　slipped in there??

Is it: 両親が帰って来ない＿＿＿＿＿＿そうじをしいなければなりません。
or : 両親が帰って来ない＿＿＿＿＿＿そうじをしなければなりません。

if the later, the the first part mean: parents don't come home
the second part: have to clean up

if you want to say まで　you need the deadline right? but 帰ってこない　is the opposite, 帰ってくる would be needed.

so, with うちに it makes perfect sense:
within (the time) (my) parents dont come home, (i) have to clean up
(after a party or something)