A.5m/s B.6m/s C.7m/s D.9m/s
A.8m/s B.9m/s C.11m/s D.12m/s
A.交互捻鋼絲繩 B.同向捻鋼絲繩 C.對(duì)稱(chēng)左右捻鋼絲繩 D.左右捻鋼絲繩