单项选择题
A.the towboat vibrates when backing down
B.the roostertail exceeds the height of the main deck
C.a strain is placed on the face wires
D.water comes over the foredeck of the lead barges
单项选择题 A tow of 9 barges is made up three abreast and three long. The towboat is faced up to the center string which is known as the（）.
单项选择题 A spreader bar is used to（）.
单项选择题 A situation has occurred in which your vessel must be towed. When the towing vessel passes the towing line to you，you should secure the line（）.