입은 치마 past tense 입던 치마 incomplete past tense 입었던 치마 incomplete past perfect tense 그녀가 입은 치마를 보았다 I saw the skirt that she wore.(She is wearing that skirt at that moment) 그녀가 입던 치마를 보았다. I saw the skirt that she used to wear.(I'm not sure she wear that skirt nowadays) 그녀가 입었던 치마를 보았다 I saw the skirt that she have worn.(I'm sure she didn't wear that skirt anymore)