It has been more than half a year since I wrote the book "GRE reading question source essence". Until the deadline of last month, the picture reflected in my mind is the learning process of myself and my friends over the years. I used to think: time is the most dynamic thing in the world, and other people, things and knowledge are relatively static objective existence; Now it is not: everything in the world is constantly evolving, only time is relatively static, and the length of every second...