There are tips and notes for every lesson, but they are only visible in the web app. https://www.duolingo.com/skill/ru/Possessive-Modifiers-1
Tips and notes
POSSESSIVE ENEMY MINE
There isn't much to say about words like "my" or "your" in Russian.
his/her/their do not change: его́, её, их(and they don't get an initial Н after prepositions!)
my/your/our roughly follow an adjectival pattern, i.e. they copy the gender and the case of the noun they describe. Just like этот:
Unlike English, no distinction is made between my and mine, her and hers etc.
Pronunciation: in «его», as well as in adjective endings and "сегодня" the letter Г is pronounced В. It is a historical spelling.
Nouns in Russian belong to one of three genders: feminine, masculine or neuter. If a noun means a person of a certain gender, use that one. For all other nouns look at the end of the word:
(TABLE) ENDING IN NOM; GENDER; EXAMPLES
-а/-я ; feminine ; ма́ма, земля́, Росси́я, маши́на
consonant ; masculine ; сок, ма́льчик, чай, интерне́т, апельси́н
-о/-е ; neuter ; окно́, яйцо́, мо́ре
-ь ; feminine or masculine - consult a dictionary ; ло́шадь, ночь, мать, любо́вь / день, конь, медве́дь, учи́тель
IF THERE'S A SOFT SIGN, IT ISN'T POSSIBLE TO PREDICT THE GENDER, AT LEAST, NOT ACCURATELY. HOWEVER, ABOUT 65-70% OF THE MOST USED NOUNS THAT END IN -Ь ARE FEMININE. ALSO, YOU CAN LEARN THE COMMON SUFFIXES ENDING IN A SOFT SIGN THAT PRODUCE A WORD OF A PREDICTABLE GENDER. THEY ARE:
-ость/-есть, -знь → feminine
-тель, -арь, -ырь → masculine
ALL NOUNS WITH -ЧЬ, ЩЬ, -ШЬ, -ЖЬ AT THE END ARE FEMININE. THE CONVENTION IS TO SPELL FEMININE NOUNS WITH A SOFT SIGN AND MASCULINE ONES WITHOUT ONE: НОЖ, ЛУЧ, МУЖ, ДУШ. IT DOESN'T AFFECT PRONUNCIATION, ANYWAY.
The convenience it serves mobile users like myself and countless others far outweighs the slight "annoyance" you may personally feel from this post. It's not like he's posting anything hateful or spamming, these tips are very helpful and without them the lessons can be confusing. Once the tips and notes are available on mobile then of course posting this would be redundant, but until then it's the best option we mobile users have.
It matters in English as well, but firstly even in languages in which word order is significant (as opposed to Latin) sometimes the adjective comes after the noun, as in French. Secondly I just got a different sentence wrong recently because the English equivalent had the word order reversed: "Excuse me, is it evening already?" The correct Russian translation was "Извините, уже вечер?" which of course places "already" before "evening". Perhaps the English was written incorrectly, but there needs to be consistency if word order does indeed matter.
"ета" means "this", which is used when the cat is close by. In this case it's simple "cat yours" ---> "Is the cat yours?" where "Is" is dropped in Russian and "the/a" has no use.
So, "Is this cat yours?" means the cat is close by and your asking the question pointing at it, where as "Is the cat yours?" is simply asking about the cat that you are already talking about or noticing.
In a way, yes, but it would be твоя, а не твой. It depends on who your audience is. If you're talking to a stranger or to a couple of kids who are looking for their lost cat, you'd say ваша. If you're at a friend's house and you see a new furry face peep her head around the corner, you could say кошка твоя?