"We are in Russia."

Translation: Мы в России.

[JoelVaissi]

When is it Россия, and when is it России, and so forth?

[deactivated user]

Russian nouns have several case forms. For the noun 'Росси́я', you can see them all here (click on the 'Declension of Росси́я' box; you probably won't need the plurals). It would take too much time to describe the functions of all the cases here, it's really better to learn them one-by-one as you progress through the course.

If you want to get a glimpse of the cases, you can look here (among other places).

[Bozbox]

so, just to be totally clear, following the diagram on the Wiki, the ending is because it's preceded by a preposition (the "prepositional" form россии, rather than the dative or the genitive)?

[elsantodel90]

It is because it is used to indicate location with a preposition that uses the prepositional case (the common ones are only "На", "В" and "О").

Other prepositions use the genitive instead, like "Возле", "У", and many others.

[AdamzGray]

So basically when talking about russia, you use Россия, and when you're talking about AT, IN, ON, FROM russia, meaning any position about russia, its России.
Example: Я ем россия. Я в России.

[Riidko]

Your take on the Prepositional case seems to be pretty close.

• 《Я в России.》 --> I am in Russia. (Prepositional)
• 《Он из России.》 --> He is from Russia. (Genitive, NOT the Prepositional, however it is identical to the Prepositional)

However, it would not be, Я ем Россия. When a noun is the direct object of a verb - in your example «Россия» is the direct object of the verb «ем» - you must use the Accusative case.

• 《Я ем Россию.》 --> I am eating Russia. (Accusative)

[AJShadow2]

Why can't I write "россия" instead of "россии"?

[Straw_Neige]

Hi, I wish you could help me. What's the function of “в" in this sentence?

[deactivated user]

It's a preposition like English 'in'.

The English 'are' (as well as 'is') is usually left untrasnlated in Russian in present tense.

[Straw_Neige]

Thank you very much! :)

[AdriHaikal]

in?

[Sam_Hudge]

Which case is used here, after в? Is it genitive case? If it's the prepositional case, it should be Россие right? Thanks

[elsantodel90]

It is prepositional. But feminine words with the ending "ия" (as opposed to just я like неделя) have a different rule where they take the form "ии". They are very common for countries (Россия, Германия).

You can always check all the cases for a word in wiktionary:

https://en.wiktionary.org/wiki/%D0%A0%D0%BE%D1%81%D1%81%D0%B8%D1%8F