Nikkos, it is not a typo - it is correct. There are basically just two forms, quale (singular) and quali (plural). The 'e' is dropped because that's what happens phonetically anyway. You don't need to put an apostrophe. It's just one of those funny little things to remember! :)
"Quale" means 'which'. "Qual é" means 'what's or which is'. "Qual" means 'what, such'. For instance: "Quale colore ti piace?" 'Which color do you like?', "Qual buon vento?" (what good wind?) 'To what do I owe the pleasure of seeing you?'. But also : "Nel qual caso..." (In such case...) 'Then...'.
I believe that this sentence "Qual é il tuo libro" to translate is to help one understands the usage of "Qual". I kept it simple and translate as is - "Qual é" for "Which is", "il tuo libro" for "your book".
If the sentence to translate is "Quale libro è il vostro?", then it is understandable to expect Duolingo to accept the translation to be "Which book is yours?", and to report if otherwise.
I feel as one learn of another's language, one should be humble and stop insisting that the sentence construction for the English translations should be that of one's suggestion.
This is, after all, a course to learn Italian.
I use the comments section to learn more about the usage of the words in question, for example, learning the difference between "Qual" and "Quale".
I enjoyed reading the comments for "Quale balena?" as that has helped me remember "Quale" means "Which". I made a guess that "Qual è" could also mean "Which is".
If you still feel that "Which book is yours?" should be accepted as the translation for "Qual è il tuo libro?", please look at these examples.
Q1: "Which is your wife / girlfriend / secret lover?"
Q2: "Which woman is your wife / girlfriend / secret lover?"
Q3: "Which wife / girlfriend / secret lover is yours?"
I hope this would help you see that "Qual è il tuo libro?" is not "Which book is yours?".
Let's keep it simple, translate and not rephrase.
Enjoy your e-learning on Duolingo!
Qual and Quale are pretty much interchangeable, but they are not exactly the same thing.
Quale means 'which' whereas qual really means 'which one'.
Grammatically, quale is an adjective (because it describes a noun), whereas qual is a pronoun. Remember qual means 'which one' so it is replacing a noun, making it a pronoun.
Qual is always singular. If you want to say 'which ones' then you have to use 'Quali'. That means Quali can be either an adjective or a pronoun depending on whether you want to translate it to just 'which' or 'which ones'.
Does each sentence to be translated stand on its own, not in the context of the previous one? Q1 asked for "I am reading a book" or some such. Next, at least in normal conversation, would be "What book?" or "Which book are you reading?" "Which book is yours," which might be the more accurate narrow translation in this case, isn't natural in this context.
I moved to Italy after starting Duolingo. So far, Italians in Rome understand me when I ask, "Qual libro è il tuo?" They get it perfectly. So I think this is just conversational nuance and Duolingo is teaching the most grammatically correct answer. I didn't see this before. Once you start speaking Italian with real Italians, it is amazing how much gets across even if you are not schoolbook correct. I wonder if that is true for more languages?
I almost always use my smartphone or tablet for Duo. It is amazing to me how often I make a stupid mistake clicking on the building blocks to quickly and muss one or pick up the wrong one. It actually mostly happens translating into English because I am apparently not only more confident but also more careless.
Duo doesn't mark down for accents, even when not adding them means you actually wrote a different word. But they do sometimes fluke. Most of the time it's just a momentary lapse for them, but occasionally it may be somehow related to your connection as it only gets better when you go out of Duo or reboot.
I agree it can be difficult. The trick, though, is to keep playing the fast version over and over again. It takes time, but the slow version is saying only one word at a time. You'll never hear how the sounds change slightly based on the sound that comes next. The slow mode will help you hear the words, but not really help you hear the sentence. That takes time.
Duo wants you to be very sensitive to sentence structure. In this sentence cual is a pronoun and is the subject of the sentence. In your sentence which is an adjective modifying book which is the subject of the sentence. While not generally true of these simple sentences on Duo, such a difference can effect the use or meaning of the sentence.
Your English teacher is mistaken. If you look at definition one in Dictionary.com you will see that which do you want is one example. Which does not have to directly modify a stated noun, it can simply stand in for it as a pronoun. I am also an English teacher.
Which does not need to precede the noun. You could be looking at a group of your papers. One is a poem, one is a short story, one is a report. Someone might ask which is your report. Since all the papers are yours and they are not all reports in this case it would actually be incorrect to say which report is yours. Which is your report is the only valid question. Now in many cases both questions are asking basically the same thing, but neither is grammatically wrong in English. But because it does have somewhat different uses, mirroring the structure of the Italian sentence is important.
The distinction between what and which is not quite parallel between Italian and English, but quale is more like which than what. If you are choosing among things quale is generally the appropriate word as is which. As for why it is not quale, before a singular masculine noun the e is dropped.
OK. Duo is being very literal and definitive here because it is trying to draw a parallel between the Italian che vs qual and the English what and which. Strictly speaking, it makes sense, but common usage often blurs the differences, and the direct parallel between the languages is also not complete. What asks for essential characteristics of something - a type of definition. Which asks for you to identify the property that distinquishes it from others in the same category, although the category is implied by the context. If asking about your book in the realm of all books, you might say a novel, or the name of the book, but if the category were the books on your desk, you would probably say the one on the right or the red one. Of course there are always conceptual overlaps. I think almost anyone would consider the title of a book one of its essential qualities, and certainly the color is. The difference is more the difference in intent of the asker. The distinction is valid in English theoretically, but as a practical matter that's not quite how we use which in English. When we say which in English, it almost always is when there is a clear set of choices, either those available in front of you or as defined in the parameters of your conversation. If I saw you reading a book and had no idea what you were reading, I would ask what. But if I knew that you had to be reading a book from a particular reading list, I would ask which. Italian uses which for everything that has finite options, even when you don't know all of the options, and certainly when they are not in front of you. But obviously what Duo was trying to do didn't work. I might have said it worked if you were just sitting here fuming about being marked wrong, but if you don't even understand the point they were trying to make, obviously they need a new tactic.
I understand that. I agree that Duo should allow that translation as it is the more natural one. I admittedly get overly literal, but you did ask why, so I was explaining why I thought Duo made that determination even though I disagree. I have found that looking for the why's of some of Duo's tactics has at least given me some further linguistic insight instead of ONLY leaving me frustrated. Of course I still do get frustrated.