单项选择题
A.Taglines are wire rope purchases that raise and lower the jib
B.Taglines are wire ropes for horizontal positioning of the rider block
C.Taglines can be fastened to corners of vehicles or containers
D.The crane might not have taglines installed in its rigging system
单项选择题 Which statement comparing a shipboard crane to conventional gear is TRUE（）.
单项选择题 Which part provides for transverse control and positioning of a boom in a conventional yard and stay system（）.
单项选择题 Which part of a conventional cargo gear rig provides for vertical control and positioning of a boom（）.