单项选择题
The process of lowering a boom to a horizontal position and onto its deck support is called（）.
A.spotting a boom B.collaring a boom C.cradling a boom D.toppling a boom
单项选择题 The minimum length of a boat painter for a lifeboat in ocean service is（）.
单项选择题 The margin plate is the（）.
单项选择题 The main advantage and chief characteristic of a Steulchen boom is that it can be（）.
