Why is "aus" not needed? How does one construct these "compound nouns"?
For measurements there is no preposition in German to link the two nouns. You just say "ein Teelöffel Zucker" or "eine Tasse Kaffee."
That's because Saft is technically in the genitive case, but since nouns rarely decline in German now, it appears to be nominative because there is no article.
The 'quantity_ingredient' format (with no "of") is technically not correct in English (at least not American English) and only used in abbreviated recipes or product labels. Since this sentence uses "please!" the speaker is clearly requesting/ordering 10 liters of juice, not writing a recipe or reading the label of an (improbable) 10-liter bottle of juice.
No, it is completely acceptable in American English to say 10 liters juice. The "of" is not necessary.
Only in certain contexts, like a recipe or a list. I googled "liters of juice" (with quotes) - 173,000 results. "liters juice" (with quotes) yields 2740 results and, after perusing the first 20, I stand behind what I said. Perhaps there is a region of the U.S. where the "of" is truly optional, but it sounds unnatural to me without it.
And the same goes for British English. If you said "10 litres juice" it would be understood, but that does not make it correct.
Spoken language is different from what you could say book language. You won't find "Ya'll got..." in any grammar books for example, even if it is common :)
I agree that your answer should have been correct. Technicalities aside, I think the quantity at some point changes the context. For instance, I would never say "A cup coffee, please," however I have often said and heard "Ten gallons premium, please."
So I'm guessing that 'Liter' can mean 'litres of'? (I love writing litre instead of liter - it seems so refined)
If we were to add "Ein" at the beginning of the sentence, we could then have one of those famous, long German words for a packaging of 10 L of juice..
You misspelled zehn.
You used a lowercase first letter for the nouns Liter and Saft.
You used the preposition aus (roughly, "out of" or "made from") which makes little sense here -- the litres are not made of juice; they just measure how much juice you have.
German doesn't use a preposition there at all; it's simply zehn Liter Saft, drei Meter Stoff, fünf Kilo Reis etc. For ten litres of juice, three metres of fabric, five kilograms of rice.
Now the way I have experienced it, “Saft“ is used for just about any fruit- or berry-based beverage, be it juice, syrup or soda-pops.
Am I remembering correctly that the imperative in German requires an exclamation point for punctuation?
It does not. Just as in English, an exclamation point just shows that the command (or any sentence) is shouted or is somehow more urgent or forceful. If a command is said calmly, you wouldn't use an exclamation point.
I did notice the exclamation point does seem to be pretty common on the imperatives.
That would be equivalent to something like:
Ten liters from the juice, please
So annoyed at the American English, it's litres not liters! If I spelled something the wrong way in German it's a different story.
If Duo isn't accepting "litres" for the English word, report it. In my experience, British spellings seem to be generally accepted, but some have perhaps been missed. The German word, on the other hand, is only spelled "Liter."
What was your entire answer, though? Sometimes if you write a wrong answer, Duo will just show you a random correct answer, so it's possible that something else was wrong with your answer and Duo's random correct answer just happened to use the American spelling.
With that said though, there's nothing wrong with the "liter" spelling; it's used by the 300+ million people who live in the US. Learn to accept both spellings; neither is wrong. Duolingo is an American company and teaches US English, so keep that in mind as you use the site; it doesn't always include all British spellings.
I said "10.567 quarts of juice, please." It was rejected. Don't they realize that some of us are American and can't figure out the metric system?
In English there is no such word as 'liter', the correct English spelling is 'litre' .
In English there is no such word as 'liter'
Yes, there is: https://www.merriam-webster.com/dictionary/liter
the correct English spelling is 'litre'
That is a correct spelling but not the (only) correct spelling.
English is a pluricentric language, which means there is more than one written standard, but all of them are "English".