29. 船舶推進軸系中，下列何者不包括在內？ (A) 凸輪軸及其軸承 (B) 中間軸及其軸承 (C) 艉軸及其軸承 (D) 推力軸及其軸承

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