[pacerier]

thanks alot for the replies, they really do clear up alot of misunderstandings. i think for now i'll stick to using [v]なくてはならない and [v]ないといけない.
As for the word 駄目, is it common to write it in ダメ?


also, i found this sentence in a guide: ボブに電話して買いものに行かなければならない.
Does the sentence mean that "i will call Bob and i must go shopping", or that "i must call Bob and i must go shopping"?


Regarding the てばかり conjugation, does it imply “disapproval”, in other words will ボブ勉強してばかり mean “Bob does nothing but study, and I’m not pleased with it”