All the question and answers are added / updated on our website collectively by Mariners like you. The PDF is a copy of the web-pages (freely available on our website), particular to your selection for MMD / MCA Orals Question selection ! For some sections, specially Engine Department, it seems mariners have not posted many answers !
While some questions may have answers, for questions without any answer in the PDF/Web-page it means that nobody has posted answer for that particular selection which you chose and downloaded. We are sorry but if this is the case, we do not have answers in our database ! Remember this is a community based website and you can help other mariners by posting answers which you may know.
While we thought same was obvious, but on feedback of our friend Animesh Sen and Akash Shiromani, we are now highlighting the number of Answered questions too. Thanks Akash for this feedback. Hope this brings more transparency and users are better informed prior buying the Question Sets.