"I am vegetarian" --> "Sono vegetariano" or "Sono vegetariana".
"You are vegetarian --> "Sei vegetariano" or "Sei vegetariana".
"He is vegetarian" --> "È vegetariano".
"She is vegetarian --> "È vegetariana".
"We are vegetarian(s)" --> "Siamo vegetariani" or "Siamo vegetariane".
"Y'all are vegetarian(s)" --> "Siete vegetariani" or "Siete vegetariane".
"They are vegetarian(s)" --> Sono vegetariani" or "Sono vegetariane".
"il" in the singular and "i" in the plural can't be used before vowels, so you need the counterpart (lo/gli). If you know how to use "il" as opposed to "lo" in the singular, you should have no problem knowing that "i" and "gli" follow the exact same rules in the plural.
In a different discussion someone linked to this article: http://blogs.transparent.com/italian/using-the-definite-article/
From what I've gathered you use a definite article before certain words and when you're using nouns "in a general, collective sense". I would think that this implies that "Non mangio gli animali." means something like "I don't eat animals (in general).", e.g. because I am a vegetarian, and that "Non mangio animali." could be closer to "I am not eating animals (right now, ...).", e.g. because I am eating something else at the moment.
However, I am no expert either, and I think it would be nice if some native speaker or advanced student could comment on this and clarify things.
Different language, different grammar rules. Translation is not about going literally word-for-word. It's about how each language says it.
Specifically here, Italian and English use "the" differently for the general case vs a specific instance.
In English, if we say (for example) "I eat/drink the whatever", that's a specific instance. If we say "I eat/drink whatever", that's the general case.
In Italian, it's the other way around.
I don't get this. Animali ends with i therefore it is masculine. I tried looking up the singular version of the word and I got animale. Why animale and not animalo? just like Ragazzo & Ragazzi, Raggaza & Ragazze - I thought that if a plural of a word ends with i the singular should end with o, since it's masculine... Is this an exception or am I just missing something?
To answer the question more directly, although most nouns in Italian are regular:
-o = singular masculine
-i = plural masculine
-a = singular feminine
-e = plural feminine
Some are irregular. They are
-e in the singular and
-i in the plural and you need to memorize on a case-by-case basis whether they are masculine or feminine.
Synonyms are generally interchangeable. These are different forms that are used in different situations and are not interchangeable, a little like "a" and "an" are generally the same thing, but "a" is used before words that start with a consonant sound and "an" is used before words that start with a vowel sound.
Why is ' gli' not translated in the original sentence ? The inclusion of the definite article changes the meaning from general to specific terms. I do not eat animals isn't the same as ' I do not eat the animals' The word the specifies a group of animals, leaving it out changes the sense. Any opinions ?
non does not mean
English has something in its grammar called do-support that the Romance languages do not have.
If I were to re-write the above without do-support, it would look like this:
non means not
English has something in its grammar called do-support that the Romance languages have not.
It's a difference in English vs Italian grammar. But you cannot say that "not" translates as "don't".
Duolingo isn't teaching anyone to do anything except be able to speak a new language. No one is going to change their diet just because they learned how to say something. No one benefits from the mindset of "I don't like X, so I'm just going to pretend it doesn't exist." Knowing how to say something has absolutely nothing to do with whether you approve or disapprove of it. You can't have conversations with other people and hope to change their minds about something if you don't have the words to talk about it.