单项选择题
A.prevent them from falling when the vessel rolls B.protect personnel from electrical shock C.increase their operating efficiency D.prevent unauthorized personnel from operating them
All echo-sounders can measure the（）.A.actual depth of w...
单项选择题All echo-sounders can measure the（）.
A.actual depth of water B.actual depth of water below keel C.average depth from waterline to hard bottom D.average depth of water to soft bottom
Aboard ship，vertical flat plates running transversely a...
单项选择题Aboard ship，vertical flat plates running transversely and connecting the vertical keel to the margin plates are called（）.
A.floors B.intercostals C.girders D.stringers
A wooden float placed between a ship and a dock to prev...
单项选择题A wooden float placed between a ship and a dock to prevent damage to both is called a（）.
A.camel B.dolphin C.rat guard D.wedge
