Hi, I feel like learning Korean again by answering this kind of question. Here are some examples for "formal endings to sentence". 가다 = go (basic form) 간다 = will go / be going 갔다 = went 가겠다 = will go 가시다 = go (respectfully speaking) 갑니다 = will go / be going 가신다 = be going (respectfully speaking) 가시었다 = went (respectfully speaking) 가시겠다 = will go (respectfully speaking) 갔겠다 = might go 갔습니다 = went (respectfully speaking) 가겠습니다 가시었습니다 가시겠습니다 갔겠습니다 가시었겠다 가시었겠습니다 ... I give up here. These various endings are quoted from http://home.freechal.com/hangeuljapan/03/1/28933689 (in Korean).

Some are isseoyo, seupnida, ayo, eoyo, yeoyo, yeyo, eyo.....

From what I know, there are so many endings that I read. :)