Breakdown of Чьи это синие джинсы?
это
this / it is
чей
whose (m, sister forms: чья, чьё)
синий
dark blue
джинсы
jeans
Questions & Answers about Чьи это синие джинсы?
Why is "whose" translated as чьи here instead of чей?
Because джинсы (jeans) is plural. In Russian, question words like "whose" act like adjectives and must match the noun they refer to in gender and number. Since джинсы is plural, we use the plural form чьи.
If джинсы is plural, why do we use это instead of the plural эти?
When you say "this is" or "these are" to identify something, Russian always uses the fixed word это, no matter if the noun is plural, masculine, or feminine. You would only use эти if it were directly attached to the noun, like in the phrase эти синие джинсы (these blue jeans).
Why does the adjective синие end in -ие rather than the usual plural ending -ые?
Most adjectives in the plural end in -ые (like старые for "old"). But синий (blue) is what we call a "soft" adjective. Because its stem ends softly, it takes the soft plural ending -ие to match.
Is джинсы always plural in Russian, like it is in English?
Yes! джинсы is a word that only exists in the plural form, exactly like "jeans" or "pants" in English. That is why every word describing it in this sentence has to be in the plural form.