던 적 있다

have you ever done that before?

-던 적 있다 asks or states whether there was ever an occasion of something in the past: 미국에서 살았던 적 있어요? (have you ever lived in America?), 제일 좀 인생에서 힘들었던 적 있어요?. Textbooks usually teach -(으)ㄴ 적 있다 for 'have you ever'; the -던/-었던 version leans on the experience as a stretch of time that is now finished.

Register: neutral; common in interview questions