Russian Language Stack Exchange is a question and answer site for students, teachers, and linguists wanting to discuss the finer points of the Russian language. It only takes a minute to sign up.
Sign up to join this community
Он работает с двух часов.
After the preposition "с" (=since,from) we need to use the genitive case. "двух" is in genitive and as far as I know, два requires the noun to be in genitive singular(часа) after itself. But in the above sentence it is in genitive plural("часов"). Why?
Indeed с governs genitive when it means from (с двух часов, убрать со стола, слезть с дерева). It governs instrumental when it means with (картошка со сметаной, поговорить с клиентом, пойти в кино с девушкой).
When the case is neither nominative nor accusative, numericals do not affect the case or number of the following noun (or intervening adjectives). There is only one exception to that rule: numericals which end by один/одна/одно still govern singlular.
So what is going on in your sentence он работает с двух часов? The preposition с governs genitive, and, since the case is not nominative or accusative, the numerical два is now powerless to affect the following noun.
Finally, there is a caveat with the word час. In this word, if the genitive case is due to numerical, e. g. два (три, четыре) часа́ the stress is on the last syllable. If the genitive case is due to other cases (e. g. «Бодрствуйте, потому что не знаете ни дня, ни ча́са» - Евангелие от Матфея), the stress is on the first syllable. I don't know why, and cannot think of other similar words.
