I didn't expect I can pass it today. Last night I got 49% on the bonus master exam; the day before yesterday I got 51% on the master exam with K&B Book. So I just wanted to try a paid mock exam today.
Today I spent 2 hours to finish all questions and 1 hour to review them. I changed answer for 6 questions, which I believe the first answer was wrong. But I didn't review any drag questions, I think they are slightly easier, more focus on grammar; and if you review them, you lose your answer!
If you can pass two mock exams with the book, you definitly can pass the real exam!