A、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 14px">前进向上，强制切土</span>
B、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 14px">后退向下，强制切土</span>
C、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 14px">后退向下，自重切土</span>
D、<span style="FONT-FAMILY: 宋体; FONT-SIZE: 14px">直上直下，自重切土</span>