把模式P中的字符分成两个子段P1和P2,它们分别称为P的两个子模式，在正文中先找到子模式P1的出现，再比较子模式P2中的字符，如果P2中的字符也匹配，则再正文中模式P发生一次匹配；否则，在正文中再找P1的第二次及以后的各次出现。-The characters in P mode is divided into two sub-paragraph P1 and P2, they are known as the P of two sub-model, first found in the body of the emergence of sub-models P1, P2 and then compare sub-model characters, if characters in P2 also match, then again the body of a single pattern P matching　Otherwise, find the body of P1 in the second and subsequent emergence.