There is an awful lot of opinions re this exercise. As a native Finn, having lived in the UK with my thoroughly English husband for an awfully long time, I would say that the Finnish sentence does not imply only one of these options - it covers both. In general: berries grow in a/the forest. They can, of course, also grow in a garden. From the Finnish sentence, you can't even say if it refers to a forest in general or a specific forest, hence the 'a/the'. Specific berries in a specific forest: the berries are growing(because they really are growing right now) in the forest.
"The berries are growing in the forest", "Berries are growing in the forest", "The berries grow in the forest", and "Berries grow in the forest" are all grammatical English sentences, albeit with slightly different meanings.
The first sentence has the berries, and we know which ones, growing in the forest right now.
The second sentence has some berries, and we might not know which ones, growing in the forest right now. Most people would reword this to "There are berries growing in the forest", but the dummy subject "there" isn't strictly necessary. It's a stylistic choice, but nowadays the most common choice.
The third sentence has the berries, we know which ones, habitually growing in the forest. They might not be growing there at this exact moment, but they regularly grow there.
The fourth sentence has some berries, we might not know which ones, habitually growing in the forest.
However, I don't think all four of these English sentences should be translated as "Marjat kasvavat metsässä".
Yep, that's an example where it's used existentially. Marjoja is not technically the subject of this sentence but more like a predicate complement and that's why the verb doesn't agree with marjoja anymore.
It's the same as when you say "Minulla on kissoja." (I have cats. / "At me there are cats.") The kissoja is existential, a predicate complement rather than the subject and on is used rather than ovat because 3rd person singular is the default verb form for these subjectless existential sentences.
It's a bit like in German or somewhat old fashioned English:
There grow berries in the forest.
Es wachsen Beeren im Wald.
In both English and German though, the verb agrees with "berries" though, meaning that it really is the subject, which is particularly surprising in German as es really looks as if it should be the subject.
Tiellä ajaa autoja is another example of this structure, but I can't reply to JANBOEVINK. Duolingo has a depth limit in these forums.
Subjects can be partitive, and can be partitive plural. I've seen sentences like "Miehiä kävelee", where miehiä, despite being the partitive plural of mies, is the subject.
When a subject is partitive singular, the verb is singular. When a subject is partitive plural, the verb is still singular. A partitive subject always has a singular verb.
According to https://uusikielemme.fi/finnish-grammar/syntax/sentence-types/t-plural-vs-partitive-plural, the plural subject of an existential sentence would be plural partitive.
So according to this website, marjoja would be the subject of "Metsässä kasvaa marjoja".
From my general reading of grammar on Wikipedia, I'd call metsässä either the adverbial complement or adverbial predicative expression.
I wrote: Too obvious, Liz, thank you!! I am modifying this comment 9 hours later. -Marjoja- is plural partitive. It is the subject of Liz' sentence, so nominative, as in English. I am surprised by the use of -kasvaa-, 3rd person singular, since I would expect 3rd person plural form, viz -kasvavat-. My Finnish contact tells me that -kasvaa- is used, overruling logic, as languages do. In a dictionary I found the sentence: -Tiellä ajaa autoja- ¨Cars drive on a / the road¨, confirming that the plural partitive uses the 3rd person singular of the verb. Clearly I did not know this.
Hi, marjoja is partitive and it can be used in this sentence but then it means something else (I confirmed my initial intuition with my native speaker boyfriend). The sentence was supposed to be berries grow in the forest - and then it sounds best to say marjat kasvavat metsässä. You can also say metsässä kasvaa marjoja but then its more like "there are berries growing in the forest". It's one of those cases, happens in finnish also with verb olla, that in certain structures you drop the subject, if that makes sense.
But we only need “The berries are growing in the forest” Marjat kasvavat metsässä. All seems ok for DL learning purposes. I don’t think anything needs to be changed in the sentences. I’m not suggesting removing “the” or changing to partitive. And I am pretty sure they wrote things as they did to emphasize the use of this plural form as particular multiple objects.
One acceptable translation to English should be without "the" as an affirmative statement
"Berries grow in the forest"
I can't see anything wrong with that
Marjat is not definite. It is nominative rather than partitive. Because it's the subject of this sentence and it's not an existential sentence (e.g. "There are berries growing ..."), it has to be in the nominative case, whether it's definite or indefinite.
Marjat kasvavat metsässä. = (The) berries grow in the forest.
Metsässä kasvaa marjoja. = There are berries growing in the forest.
This is a very relevant comment, viz that -Marjat- can be translated as -berries- and that this does not require the partitive form. Clearly this also supports Stiofan28 above. I do not understand the concept of "predicate complement" but it does seem to relate to Lena's comment that the sentence would mean something else with -marjoja- at the start of it in place of -marjat-. Lena does not explain what else it would mean. I would be curious to know.
Thank you for all the replies. I actually wrote "Berries grow in the forest" too, and not just once, was just trying to figure out potential logic the creators used to translate this in their particular way. Sometimes they seem to get strict about this or that translation to emphasize some particular structure in Finnish, and we all are trying to figure it out :)))