I am trying to fully understand these words in English language (I know this is a Russian Stack Exchange site but I think this is a proper place to ask this question). So in Russian you can say: - Я должен сделать что-то (I must? Should?) - Мне нужно сделать что-то (I need?) - Я обязан сделать что-то - Мне необходимо сделать что-то - Мне следует сделать что-то (should?) And I am not quite sure what English words I need to use for these situations and also if they are directly translatable (as must is always = должен?). Appreciate any feedback and clarification.
The topic is too vast to cover it here. The simplistic answer would be
must = обязан / должно быть
need = нужно / надо / необходимо
should = следует / следовало бы
have to = должен
have to would be synonymous if applied to oneself as in I must go = I have to go and mean
There's also nowadays rarely used
ought to which i believe is mostly synonymous with
And also often there won't be a one to one or consistent translation of the modal words because their use cases in two languages may differ. The more idiomatic translation of the above mentioned I must go = I have to go into Russian in my opinion would be
мне нужно/надо идти rather than
я должен идти, despite the use of must/have to in the original.