单项选择题
A.fire-tubes B.furnaces C.down-comers D.soot-blowers
（） system is arranged to ensure that water can be drawn...
单项选择题（） 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
（） connected to the moving tiller will bring the floati...
单项选择题（） 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
Two rams of the hydraulic gear are linked at their oute...
单项选择题Two rams of the hydraulic gear are linked at their outer ends to （） by a crosshead and swivel block.
A.the piston rod B.the tiller arm C.the connecting rod D.the rudder
