Adjectives
• My first question is why верующим has to be instrumental in this case:
Я не знал, что они верующими.
• Secondly, why is доброй ночи in genitive? Does a noun have to be in genitive if it's in an imperative or wishful fashion?

Question

Adjectives
• My first question is why верующим has to be instrumental in this case: 
   Я не знал, что они верующими.
• Secondly, why is доброй ночи in genitive? Does a noun have to be in genitive if it's in an imperative or wishful fashion?

Answer

1) It's a mistake. The correct phrase is Я не знал, что они верующие. The Nominative case if you use Present Tense.
2) If you mean Я не знал, что они БЫЛИ (Past Tense) верующими, it should be the  Instrumental case.
3) Because when we say Доброй ночи! we actually mean Я желаю тебе доброй ночи. (= I wish you a good night). That is why we use the genitive case.

Answer

Actually, it doesn't have to be instrumental in this case .. it should be "я не знал, что они верующие".
"Я не знал, что они верующими." - just sounds wrong.
It's possible to say "я не знал, что они были верующими" though.

Answers · 3

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