單項(xiàng)選擇題

All electrical appliances aboard a vessel should be grounded to（）.

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

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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

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

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