Breakdown of Ни один актёр не скрывал своего разочарования.
не
not
актёр
actor
свой
one's own
скрывать
to hide (conceal something)
Questions & Answers about Ни один актёр не скрывал своего разочарования.
Why do we need both ни and не in this sentence?
In Russian, emphatic negation using phrases like ни один (not a single / not one) always requires a double negative. You must include the negative particle не before the verb (не скрывал) to make the sentence grammatically correct.
What case is ни один актёр in, and does it change if the noun is feminine?
It is in the nominative case because not a single actor is the subject of the sentence. Ни один acts like an adjective here and must agree in gender, number, and case with the noun it modifies. If the subject were feminine, like an actress, it would change to Ни одна актриса.
Why is it своего instead of его (his) or их (their)?
Своего is a reflexive possessive pronoun meaning one's own. In Russian, when the subject of the sentence is also the owner of the object, you generally must use a form of свой. If you used его here, it would imply the actor was hiding some other man's disappointment.
Why is разочарования in the genitive case instead of the accusative?
This is due to the genitive of negation. When a verb that normally takes a direct object in the accusative case is negated (не скрывал), the object is frequently pushed into the genitive case. This rule is applied very consistently when the object is an abstract concept like разочарование (disappointment).