I bought the Pmzilla 200 questions book and have been struggling through many of the questions. I've also noticed that some of the answers I've gotten correct on other mock tests were incorrect in the Pmzilla book.

I am not sure how this is possible or why it is happening. Now I question my ability to answer with confidence. Also, the questions and answers do not use proper English. This too is somewhat of a disadvantage in terms of using this as a study tool.

Has anyone else encountered this or just me?