십시오

Most formal 'please do…'

-십시오 is the highest-formality way to tell someone to do something, the register of announcements, signs and speeches: 국내선 서비스는 1번 국제선 서비스는 2번을 눌러주십시오 'press 1 for domestic, 2 for international.' It is a command in shape but reads as deferential. Six of these eight lines are somebody quoting such a request (marked by the 라고 right after), which is how this ending most often turns up in conversation.

Register: very formal, announcements