ТыиграешьужедвачасаYou have been playing for two hours
Your playing distracts me from watching TV
УменязавтраконцертI have a performance tomorrow
Мне нужно заниматьсяIneedtopractice
Actions in process as in ‘Тыиграешьужедвачаса’ are always imperfective. When you are trying to decide what aspect to use, pay careful attention to the clues which will guide you to the correct choice. Note that expressions like ‘ужедвачаса’emphasize the duration of an action. All progressive tenses emphasize action in progress and are always translated with the imperfective aspect.