【正文】 is and, at the same time, moves parallel to that axis, it describes_____. A. a line B. a circle C. a helix D. an epllicate 2488 If a line at right angles to the axis rotates about that axis and, at the same time, moves parallel to the axis, it will generate_____. A. a helix B. a helicoidal螺旋面 C. a curve D. a cone 圓錐體 2489 If the pitch of a propeller is constant throughout the length and breadth of the blade, it is said to be of_____. A. constant pitch B. variable pitch C. uniform pitch等螺距 D. nonuniform pitch 2490 If the pitch varies radially or circumferentially, the propeller is said to be of_____.（長(zhǎng)度和寬度方向變化） A. constant pitch B. variable pitch C. uniform pitch D. nonuniform pitch 2491 The pitch ratio螺距比 of a propeller is the mean pitch divided by_____. A. the propeller diameter B. the propeller radius C. the pitch angle D. the length of helix 2492 When viewed from astern, if the propeller revolves in a clockwise direction when going ahead, it is known as_____. A. ahead direction B. astern direction C. righthanded向右旋地 D. lefthanded 2493 Wake興波 varies considerably with the form of the vessel, but, generally speaking, the bluffer 非流線型 的 the ship_____ the wake value. A. the higher B. the lower C. the faster D. the slower 2494 In moving forward, a ship imparts forward motion to the water at the sterns, this is known as_____. A. the speed of the vessel B. the speed of the propeller C. the wake D. the wake fraction 2495 A propeller of in diameter, having a mean pitch of , turning at 72 rpm, at a speed of 11 knots (), will give_____ of apparent slip. A. B. C. D. 2496 A (n)_____ is a chemical or electrochemical attack on the metal surface which may be further increased if the seawater is polluted. A. erosion剝蝕 B. corrosion侵蝕 , 腐蝕 C. cavity D. scouring沖刷 , 沖蝕 2497 A(n)_____ is a mechanical attack on the metal surface which may be due to a disturbance in the flow of the water over the blade of the propeller. A. erosion剝蝕 B. corrosion C. pitting D. dezincification脫 鋅 2498 Due to the large amount of heat picked up by the air in boiler and engine rooms, it would be_____ to maintain ambient conditions within the fort zone適宜室溫 (范圍 ) by air conditioning . A. possible B. necessary C. practicable D. impracticable 2499 Mooring winches are often bined with_____ units so that one prime mover drives both. A. crane B. hatch cover C. windlass D. steering gear 2500 The most mon forms of main drive used on deck auxiliaries are_____. A. steam plants, electric motors and pressed air B. diesel engine, hydraulic machinery and pressed air C. steam plants, electric motors and hydraulic machinery油船的貨油泵用的是蒸汽。 D. diesel engines, steam plants and hydraulic machinery 2501 Overload protection on hydraulic system is provided by the use of_____. A. stop valves B. pressure relief valves C. balance valves D. regulating speed valves 2502 It is important with all hydraulic systems to ensure that interlocking arrangements provided for pump or motor control levers are_____ before the pump driving motor can be started. A. in the pert position B. in the starboard position C. in the neutral position D. to be dismantled 2503 Which of the following hydraulic systems is not one of the three subdivision三種 of the Hydraulic drive system? A. Constant pressure system B. Variable pressure system C. Variable displacement system D. Constant volume system 2504 A variable displacement system of hydraulic drives consists of_____. A. a variable displacement axial piston pump B. a constant displacement axial piston pump C. a reciprocating piston pump D. a centrifugal pump 2505 Most anchor handling equipment incorporates_____ for mooring purposes. A. cable lifters B. spur wheels C. bollard系船柱 D. warp ends 2506 The duty of a deck winch is to lift and lower a load by means of a fixed rope on_____. A. a warp end B. a mooring winch C. a worm gear蝸輪 D. a barrel 2507 Deck cranes require_____ time to prepare for working cargo than derricks. A. less B. more C. many D. much 2508 Some cranes are mounted in pairs on a mon platform which can be rotated through_____. A. 360o B. 270o C. 180o D. 90o 2509 _____ can be operated independently or locked together and operated as a twinjob cranes of double capacity. A. Two derricks B. A derrick and a crane C. Two cranes D. A crane and a winch 2510 A fire starts when the following_____ factors e together. A. bustible material B. ignition source C. oxygen D. A and B and C 2511 Class A fires are best extinguished by quenching冷卻 or cooling with_____. A. deprival of oxygen B. a water spray C. sodaacid D. foam 2512 Class B fires are best extinguished by smothering, . A. deprival of oxygen B. removal of heat