A PhD student has to be fully devoted into their researches, at least they need to equip themselves with the relevant background and experience, with a strong passion to explore more. The longer I am staying as a PhD student, the more invisible stress that I felt, and the more I felt that I am not suitable for it. Sometimes I am just lost in this path, but i know it is the correct path. Just I haven't found a right way to get myself into it.