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單項(xiàng)選擇題

Large pipes or （） are fitted between the steam and water drums to ensure good natural circulation of water.

A.fire-tubes
B.furnaces
C.down-comers
D.soot-blowers

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單項(xiàng)選擇題

（） system is arranged to ensure that water can be drawn from any tank or the sea and discharged to any other tank or the sea as required to trim the vessel.

A.The domestic water
B.Bilge water
C.Oil transfer
D.The ballast

單項(xiàng)選擇題

（） connected to the moving tiller will bring the floating lever pivot and the lever into line at right angles to the screw shaft axis.

A.A cut-off lever
B.A swivel block
C.A cross-head
D.A driving gear

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