Breakdown of Добрый день, это моя сестра.
это
this / it is
сестра
sister
мой
my (мой, моя, моё) / mine
добрый день
good afternoon
Questions & Answers about Добрый день, это моя сестра.
Why do we use это when talking about a feminine sister?
When you introduce someone or something by saying "This is...", you always use the invariant word это, regardless of the gender or number of the noun that follows. You don't change it to match the feminine word сестра.
Where is the word for "is" in this sentence?
Russian drops the verb "to be" in the present tense. Instead of saying "This is my sister", you simply say "This my sister" (это моя сестра).
Why does Добрый end in -ый here?
Why is the word for "my" spelled моя here?
In Russian, possessive words like "my" must match the gender of the noun they belong to. Since сестра (sister) is feminine, you must use the feminine form моя instead of the masculine form мой.