Hi Anastasiya, 1. "-다" format is used for writing and speech. 1) In writing Ex. When writing a diary, "오늘은 친구들과 시내에 갔다. 쇼핑도 하고 맛있는 피자도 먹었다. 참 재밌었다." (=I went to downtown with my friends. We went shopping and had a delicious pizza. It was really fun) 2) In speech, it is considered as "반말"(that people use when talking to a friend or younger person). 2. "-어요" format is used for speech. It is considered as "존댓말"(that people use when talking to older person). Ex. Me: "Did you have a lunch?" (나: 할아버지 점심 드셨어요?) -> 존댓말 Grandfather: "Yes, I just had it." (할아버지: 그래, 방금 먹었다.) -> 반말 -------------------------------------------------------- <Original verb> - <반말> - <존댓말> 졸리다 졸리다 졸려요 쉬다 쉰다 쉬어요 있다 있다 있어요 없다 없다 없어요 -------------------------------------------------------- Hope it helps,

V + 어요 이 + 어요 => 여요. 졸리다 -> 졸리어요=>졸려요 쉬다 -> 쉬어요. 있다 -> 있어요. 없다 -> 없어요.