You should learn more knowledge in college and then master them, which is useful for your future work. There is a big difference between the difficulty of opening a book and the difficulty of closing it. The open-book topic is open-ended, and there is no formed answer, so you need to refer to it and summarize it. Closed-book exam is a dead knowledge, which is easy to remember, so as long as you master the knowledge, close the book and answer well, you don't have to listen to anyone, just prepare with it closed.