It is a way for Duo to demonstrate the while aber means but or except, sondern is something else that means but in the sense of contradiction.
This sentence definitely shows a contradiction so it definitely needs sondern instead of aber for English word but. A less clearly stated contradiction would mean the need for sondern instead of aber would not be so clear.
If you want to remember the difference between aber/but and sondern/but, this well constructed Duo example is perfect for the job.
I understand English speakers are learning that they have to use sondern in such situations in German, but native English speakers aren't going to say "That's not a book, but a coat." They're going to say "That's not a book. It's a coat." Sondern has no direct counterpart in English. But and rather make for hopelessly awkward attempts. For the purposes of learning to use sondern in German, I can see using them, but the more elegant solution, "This is not this. It's that." should be a correct answer, since that's what native English speakers do, not the but and rather stuff.
You are right the "sondern" has no direct English counterpart, which is exactly why using a naturalistic English translation would fail to fully teach the difference between "aber" and "sondern". I feel like the naturalistic translation makes more sense in other lessons, but not in the one that is specifically geared toward teaching conjunctions.
My imagination told me it was a situation like this "What is it that she wants for her birthday? Is it a book?" "No, she changed her mind. It's not a book, it's a coat instead" BUT that might just be because it's my sister's birthday next week and I am stressing out about a present XD
I suppose while the circumstances are rather rare that one would point out That is not a book but a coat there are probably a lot fewer occasions where people feel compelled to hold up a coat and patiently explain to someone This is not a book but a coat.
On the other hand I guess there might be a class of students unfamiliar with the objects in question having not seen either of them before. Or maybe their native language is so alien to German that it is hard for them to hear the different tones between the two words.
I'm not exactly sure what your question is, but I'll answer based on what I think is confusing you.
One uses the accusative einen before masculine nouns when it's the object of a sentence, as you know. I assume you're getting confused about what to use after sondern. It has to do with the verb before the comma:
- Das ist ein Mantel.
- Das ist kein Buch, sondern ein Mantel.
So, it is simply carried over to whatever comes after the sondern. Your other sentence must've had an accusative object, for example:
- Ich sehe einen Mantel.
- Ich sehe keinen Rock, sondern einen Mantel.
- Ich sehe kein Buch, sondern einen Mantel.
The reason why the verb for "to be", sein, never takes einen is because there can be no object. For example, in "he is my friend", what is the receiver of "is"? Exactly, there is none. There is a receiver in "he dislikes my friend", though (there is no X = X nature). The only other verbs that have no object (in other words, a nominative object) are werden and bleiben, as far as I know.
It is easier to think of what the verb to be means.
Something is something, positive or negative. They are the same thing within the context of that sentence. Within the context of that sentence they can be reversed. Each one is not the other. They have the same case because within that sentence they are the same thing.
Yes, there are a of words floating around in the sentence. One of those words creates a negation. There are some punctuation marks. But what counts is the verb to be. Coat and book would be presented in the same case with or without the extra stuff.
Clearly one of the somethings must be the subject of the sentence. But the other something is the same thing within that sentence. Within the sentence a coat is not a book and a book is not a coat. Therefore, both somethings are rendered in the nominative case.
That is not true for other verbs.
It's a nonsense sentence designed to show how one uses the word "sondern".
This is not a book. It's actually a coat.
It's ridiculous because most people could not confuse the two things.
This is what happens when you make sentence comparing two random nouns.
At least, because it is ludicrous, it is memorable.
What a a stupid sentence. It may be trying to reach grammar, but we should also be learning reasonable contradictions ie. That is not book, but a magazine. That is not a shirt, but a jumper, things like that. This is just throwing words together, not building a lexicon. They might as well have said, that is not a building but a kangaroo.
das = demonstrative article/pronoun pointing to something real or figurative. Das ist gut - that is good.
dass = grammatical function usually a conjunction. In English, I tell you so that/dass you will know.
that = pointer thingy
that = grammar thingy
ditto for das/dass
It's is not a translation of sondern.
What you are actually saying is that the German sentence is wrong. You would prefer a German sentence that doesn't include sondern.
Sondern is not just another word for English but. Sondern is...... not A but B. .... Not a book but a coat (inside the box, ship, boxcar; the meaning of a phrase in German; whatever)
Sondern carries the notion of replacement of contradiction. Something is something instead of something else. English it's does not carry that meaning although it doesn't deny it.
Die Eule is not so much teaching sentences--we are not becoming human phrasebooks--as using sentences to teach vocabulary and grammar.
That said, there are some phrases which are taught as vocabulary, such as Es tut mir Leid or Danke, guten Tag.
For the most part, though, it helps to forget whether one would use the offered sentences oneself, or hear them in conversation, or even read them in a book or see in a movie. Just understand why the sentence means what it does and why it's structured the way it is.
Only with certain types of conjunctions: subordinating conjunctions.
sondern is a coordinating conjunction. Another coordinating conjunction is und -- for example, Ich esse Brot und du trinkst Wasser. "I am eating bread and you are drinking water". (We don't say Ich esse Brot und du *Wasser trinkst.)
Please pay attention to the umlauts and the capitalisation -- it's Sie trägt keinen Rock, sondern einen Mantel. and Das ist kein Buch, sondern ein Mantel.
tragen (to carry, to wear) is a transitive verb -- one that takes a direct object. The object stands in the accusative case. So you have keinen Rock, einen Mantel in the accusative case.
But sein (to be) is not a transitive verb that takes an object -- you can say "the skirt is worn by her" but you can't say "the book is been by this" for "this is a book". Instead, "to be" is a copula (linking verb) that links a subject to a predicate that says something about the subject -- "this is a book" is similar to "this = a book". Such a predicate is in the nominative case in German (almost always). So you have kein Buch, ein Mantel in the nominative case.
tragen "wear" is a normal transitive verb, which takes a direct object in the accusative case -- the thing that "undergoes" or "suffers" the action of the verb, i.e. the thing that is worn.
sein "to be", on the other hand, is not an action -- it's more like the spoken equivalence of an equals sign. "this is a book" as "this = book". The thing after "is" is not the object of a verb (the book is not "been" by "this"); it's a predicate that describes the subject. Such predicates are in the nominative case in German.
Thus you have das ist ein Mantel with ein Mantel in the nominative case.
This sentence has ist as the main verb, and so the predicate on the right-hand side is in the nominative case.
The other sentence presumably had a transitive verb in it (one such as hat that takes a direct object) and so the object on the right-hand side is in the accusative case.
Das ist ein Mantel. Sie hat einen Mantel.
Why is the construction ich habe kein Buch sondern ein Mantel
It isn't. It has to be ich habe einen Mantel, not ein Mantel.
And so Ich habe kein Buch, sondern einen Mantel just like Ich trage keinen Rock, sondern einen Mantel.
Accusative case in both sentences, as the direct object of haben and tragen.
But this sentence is Das ist kein Buch, sondern ein Mantel -- the verb in the sentence is sein "to be", which does not take a direct object. It's a linking verb that links a subject to a predicate, which in German is (almost always) in the nominative case.
So you need nominative ein Mantel here, rather than accusative einen Mantel.
Because einen Mantel would be accusative case, but there is nothing here that would require the accusative case.
sein (to be) is not a transitive verb that takes a direct object in the accusative case. (One test is that you can't turn "That is a coat" into "A coat is been by that".)
It's a copula or linking verb that links a subject to a predicate -- and such predicates are (almost always) in the nominative case in German.
Thus you need nominative kein Mantel.
both the sentences have accusative case
No, they don't.
Use nominative after "to be", not accusative.
Thus Das ist ein Mantel or Du bist ein Junge -- not einen Mantel, einen Jungen.
"to be" is not a transitive verb that takes a direct object in the accusative case. (Hint: you can't form the passive voice by turning the "object" into a subject: "A boy is been by you" or "A coat is been by this" makes no sense.)
By my understanding, "kein" acts as "no" in phrases like "that's no moon..." (so the indefinite article, "a", is not needed as it would be with "not").
I would say that in English I would naturally phrase this with a gap (perhaps punctuated with either ... or — or ; or just a new sentence) instead of using "rather than" or "instead" as you would use "sondern".
"That's not a book. It's a coat!"
"That's no book... it's a coat!"
"That's no moon... it's a space station!" https://youtu.be/EVekNsgUqn4
They're both conjunctions. But "sondern" implies a contrasting situation where "but RATHER" is intended. One of the best examples you'll ever find for the correct use of "sondern" is Shakespear's "I come (rather) to bury Caesar, not praise him." In other words, "I come not to praise Caesar but (rather) to bury him." "Aber" has the sense of "however." "still," "nevertheless". ("You can inspect my briefcase, but (however) you won't find anything incriminating in it."
That is not a proper sentence, but it could be if punctuated properly.
"That is not a book; it is a coat."
What you have written, Diana670165, is called a "comma-splice".
Regardless, I speak English 99% of the time, and I absolutely would say "that is not a, but it is b." There is nothing at all wrong with it. Still, it doesn't capture the full meaning of sondern unless "instead" is also included: "that is not a, but instead it is b". NB: it is key that the first clause contain a negative.
You probably won't. No more than I will ever use "ich bin schwanger".
However, you probably will use every word in the sentence, in different order, with other words as well. By understanding how they fit together in this sentence--especially sondern--you will build an ability to create your own sentences to express thoughts that YOU want as (not after) you learn a new language.
Or you could try to commit a phrasebook to memory.