Did you know that Russian participles always have the same form (case, number and gender) as the word they depend on? If the participle clause is used after this word, comma is always put before the clause.
Я знаю человека, купившего здесь квартиру. I know the person who bought a flat here.
Телевизор, купленный на прошлой неделе, уже сломался. The TVset, which was bought last week, already got broken.
Цветы, покупаемые ею, всегда красивы. The flowers, bought by her, are always beautiful.