To move back or away from something.
He ret back from the edge of the cliff.
他從懸崖邊退了回來。
To put something back where it belongs.
She ret the book to the library.
她把書還給了圖書館。
To give something back to the person it came from.
The company ret the money to its customers.
公司將錢退還給了客戶。