밥부터 먹자 (Let’s eat first.) : We say “뭐부터 하자 (Let’s do something first)” when we suggest doing something first among a few options.
늦어서 미안해 (I am sorry for being late) : When we want to apologize for being late to an appointment, we may say “늦어서 미안해”, and then explain the reason why we are late in various ways.
어떡하지? (What should I do?) : This expression is the shortened form of “어떻게 하지? (What should I do?),” and we usually say it to ourselves while experiencing an embarrassing situation.
It is used when we leave from an appointed place after meeting a person, or when we leave the work place for home.
the Korean Tutor 