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單項(xiàng)選擇題

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

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單項(xiàng)選擇題

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

單項(xiàng)選擇題

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

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