31. 船舶推進效能, 其推進效率英文書寫下列何者正確? (A) Efficiency of engine (B) Efficiency of hull (C) Efficiency of propulsion (D) Efficiency of torsion

3. The layout of drain systems can often be improved by the use of automatic pumps. Condensate can be drained by gravity more readily to local receivers and then pumped back to the engine room as required. What type of operated traps is above description? (A) Mechanical trap (B) Thermostatic trap (C) Thermodynamic trap (D) Vacuum trap