An orifice-check valve placed in a hydraulic system is used to（）

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• In an operating diesel engine, which of the following condition is an indication of a leaking air starting valve?（）

  A . noise coming from that air starting valve B . continuous operation of the starting air compressor C . zero air pressure in the air starting system D . overheated starting air pipe to the cylinder head

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• 速腾可选装PLA智能泊车辅助功能。

  A . 正确 B . 错误

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• For an ordinary four-stroke engine the exhaust valves open （）.

  A . after TDC B . before TDC C . after BDC D . before BDC

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• If you were inspecting the valve springs on an auxiliary diesel engine, your best indication of impending spring failure would be （）

  A . a glazed surface on the spring B . nicks in the protective coating C . a build up of sludge deposits D . cracks in the surface of the spring

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• In an engine with air inlet valve and exhaust valve on its cylinder heads the fresh air will enter into the cylinder （） and the gases exhaust （）, there being an adequate overlap between the inlet opening and the exhaust closing.

  A . downwards；upwards B . upwards；downwards C . downwards；downwards D . upwards；upward

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• If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.

  A . increase the capacity of the coil B . increase the superheat at the bulb C . deliver more refrigerant to the coil D . decrease the capacity of the coil

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• For an ordinary modem marine four-stroke engine the inlet valves close （）.

  A . after TDC B . before TDC C . after BDC D . before BDC

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• A loud clicking noise from the valve compartment of an operating diesel engine would indicate（）

  A . worn valve seats B . worn main bearing C . excessive valve clearance D . weak rocker arm spring

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• PLA是指（）。

  A . 可编程逻辑阵列 B . 可编程阵列逻辑 C . 通用阵列逻辑 D . 专用阵列逻辑

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• Which action must be taken when an individual cargo tank is closed off from the inert gas system by the tank isolation valve?（）

  A . The tank must be gas freed B . The tank must be ballasted C . The tank must be vented to the atmosphere D . The bypass valve must also be closed

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• If a single cylinder relief valve on a diesel engine lists frequently while the engine is running, the cause may be an （）

  A . excessively late injection timing for each cylinder B . incorrectly adjusted intake valve timing C . incorrectly adjusted fuel injector D . incorrectly adjusted intake valve clearance

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• Excessive valve lash in an auxiliary diesel engine will cause the valves to open（）

  A . later and close sooner B . sooner and close later C . sooner and close sooner D . later and close later

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• A thermostatic expansion valve is properly controlling evaporator superheatAdjusting this valve to lower the superheat will result in a/an （）.

  A . evaporator pressure decrease B . evaporator coil over-feed C . evaporator capacity increase D . expansion valve diaphragm rupture

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• The opening of an exhaust valve on a modem, large, low-speed, main propulsion diesel engine may be actuated by （）.

  A . direct action of cam shaft B . compressed air pressure C . hydraulic “push rods” D . direct action of the main piston moving dow

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• An axial piston, variable stroke pump is used in a vessels hydraulic steering gearUnder pressure, oil continually leaks out from between the valve plate/cylinder barrel and will（）.

  A . cause loss of hydraulic oil from the system B . result in extreme damage to the pump C . cause damage to the pump ff not continually drained from the pump casing D . result in the system high side pressure to substantially drop off

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• For an ordinary four-stroke diesel engine the exhaust valves close （）.

  A . after TDC B . before TDC C . after BDC D . before BDC

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• For an ordinary four-stroke engine the inlet valves open （）

  A . after TDC B . before TDC C . after BDC D . before BDC

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• Where an excessive level of contamination is detected an alarm is sounded and diverting valves are operatedThe discharging liquid is then passed to （）.

  A . overboard B . a bilge well C . a slop tank D . a hot well

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• Broken valve strips in an operating low pressure, air compressor will cause （）.

  A、an immediate crankcase explosion B、oil contamination in the compressed air C、a decrease in compressor capacity D、no immediate loss of the compressed air capacity

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• The purpose of the safety relief valves installed on an auxiliary boiler is to （）.

  A . relieve excess fuel oil pressure during the “off” fire cycle B . admit water to the dry pipe C . throttle the forced draft fan output for proper combustion D . reduce excess steam pressure in the boiler

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• In an ordinary four-stroke engine the exhaust valves open （）

  A . after TDC B . before TDC C . after BDC D . before BDC

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• A cutoff valve in the fire-main system of a ship may be closed to protect the portion of the system on an exposed deck from（）.

  A . damage from crane operations B . being used for wash down purposes C . accidental diversion of flow to wrong location D . freezing

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• An interlock in the remote operating valve line stops the valve （） when the engine turning gear is engaged.

  A . to open B . opening C . open D . opened

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• ROM和PLA在结构上的区别，主要是ROM的与阵列______编程，而PLA的与阵列______编程。

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