单项选择题
A.On top of No.1 hatch
B.Beside the hatches，forward of the midships house
C.On top of the hatch immediately forward of the midships house
D.On top of the hatch immediately aft of the midships house
单项选择题 A towing vessel pushing a barge ahead and rigidly connected in a composite unit shall show the lights of（）.
单项选择题 A towboat is pushing barges ahead at a dangerously fast speed when（）.
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（）.