单项选择题
A.one white light B.two vertical white lights C.one yellow light D.two vertical yellow lights
A.runs from a low supporting level up to the cargo at an angle B.is also known as a distance piece C.is placed on the deck under the cargo to distribute its weight evenly D.is run horizontally from a support to the cargo
A.only when the cargo is within its rail B.after the cargo is checked by tallymen C.as soon as the cargo loading or unloading begins D.during the time when loading or unloading is going on