Questions & Answers about Я сидел перед экраном, читая субтитры.
How is the word читая formed and what does it mean here?
читая is an imperfective verbal adverb. It is formed from the verb читать (to read). To make it, you take the present tense 'they' form (читают), drop the ending, and add -я. It translates to 'while reading' and shows a secondary action happening at the exact same time as the main action (сидел).
Why is there a comma before читая?
In Russian, verbal adverbs and the extra words attached to them must always be set off by commas. This is a strict punctuation rule, unlike in English where a sentence like 'I sat reading' does not normally need a comma.
Can I use читая if someone else was reading the subtitles while I sat there?
No. A strict rule for verbal adverbs in Russian is that they must share the exact same subject as the main verb. Here, the person who sat (Я) must be the same person doing the reading (читая). If someone else was reading, you would have to use a regular conjunction like пока (while).
Why is экраном in the instrumental case here?
The preposition перед (in front of) requires the instrumental case when it describes a static location. The dictionary form is экран (screen), and adding the -ом ending makes it instrumental.