Why can't I escape from the seventh pass of Cao Cao Chuan?

This pass is like this: divide your fighting capacity into two waves, hit the following Zhang Liao, and then return in the next round and beat back seven or eight steps. The other wave hits the right, so don't hurry to take a few steps. The enemy himself came. This pass is not a victory, but a defense until about eight rounds, so you will be advised to escape, so you can leave Cao Cao where you came in from the beginning or just go forward a few steps. It is easy to escape.