例:G:S→0S1,S→01 0sS1=00S11 00S11→000s111 000S111→0000111l S→0S1→00S11→000S111→00001111 S=>+00001111 5=*S00s11>*00s11 1212 例：G： S→0S1， S→01 0S1 00S11 00S11 000S111 000S111 00001111 S 0S1 00S11 000S111 00001111 S =>+ 00001111 S =>* S 00S11 =>* 00S11