these verb are mostly need the object. 보다(watch), 먹다(eat), 마시다(drink). 하다(do). etc when you don't want to describe the object... like just eat something.. watch somehting. drink something etc... you can use thoese sentence as you may know, 먹을 , 입을, 마실, 할 etc those are very similar with 'to + verb' used as object.. 것. is something.. so 먹을 것 is something to eat.. 먹을 것을 먹다. is 'eat someting to eat'.... (it's very stange in english but koreaa use like this) last is all same 할일을 하다 'do something to do' 마실 것을 마시다 'drink something to drink' etc in my case.. I prefer to say '뭐 좀 먹고 있다.' --> i'm eatting somethig. 뭐 좀 할일이 있어서 늦을 것이다 --> i'll be late to do something myself ------------------------------------------------ 일을 보다..or usually said (볼일이 있다.) is very special expression.. in this case.. 보다. is not watch or see something.. but to do or to handle .. if you feel. it's not something to watch .. you 'd better understand it as 'do something' ex) 시험을 보다 (take a exam) 장을 보다 (go to market and buy something) etc.... --------------------------------------------------------- one more thing.. when I go to man's room..sometime i say..'볼일 좀 보고 오겠습니다." '

보다(in this case =will check on) + ㄹ(to make verb adjective and future tense) + 일(work)+보다(to check)+하러 or 러(to do) +요(ending). so it is like to check on something i will(need to) check on