1. When I was walking down the street, I slipped on a banana peel and fell on the ground. Thankfully I was alright.2. When I in school I tripped on the stairs and fell on the staircase.3. I tripped over a root and scraped my knee.
 slip on something trip on/over somethingslip 比較有滑跤的感覺，用在被香蕉皮滑倒很貼切，而 trip 指腳碰到東西而跌跤。通常後面會加 fall 表示倒下的動作。
When I was having a nose surgery I was put under lcal anesthesia.