за своим столом

at one's own desk

→ за
phrase Rare #41,932
at one's own desk Used when someone is sitting or working at their own desk or table. The form своим столом is instrumental after за.
RU: Я оставил документы за своим столом.
EN: I left the documents at my desk.

Том работал за своим столом, когда я его видел последний раз.

Tom was working at his desk the last time I saw him.

Мэри работает за своим столом.

Mary is working at her desk.

Сестра сидит за своим столом.

The sister is sitting at her desk.