Springs in fuel injectors will become not strong enough to work because______.

A．the injector opens at a lower pressure than designed

B．the needle valve and seat wear out

C．the nozzle holes wear out

D．long time in use

[单选题]Fuel injectors used in heavy fuel oil systems are usually provided with cooling to reduce（）.A . cold corrosion of the nozzlesB . fuel viscosity for better atomizationC . carbon accumulation on the nozzlesD . fuel detonation in the cylinder

[单选题]Injectors for use with heavy fuel oil must be cooled by either water or light oil to_____.A．prevent heat corrosion to internal componentsB．increase fuel delivery rate and economyC．prevent pre-ignitionD．avoid carbonization of the nozzle tips

[单选题]During the fuel injection period, fuel pressure must exceed cylinder gas pressure to （）.A . ensure penetration and distribution of the fuel in the combustion chamberB . ensure the needle valve is flushed clean during each injectionC . prevent combust

[单选题]Fuel injection systems meter fuel, atomize fuel, and （）.A . create turbulence in the combustion chamberB . aid in completing cylinder scavengingC . inject fuel at the proper timeD . minimize fuel penetration into the cylinder

[主观题]Robots,(become)increasinglyprevalentinfactoriesandindustrialplantsthroughoutthedevelopedworld,areprogrammedandengineeredtoperformindustrialtaskswithouthumanintervention.

[主观题]A． country will become richer if it, though painful, fulfils ______.

[单选题]E．nglishhasbecomeacommunication_______forpeoplefromdifferentcountries.A.meritB.streamC.enjoymentD.medium

[单选题]Whenpeoplebecomeunemployed,itis_____whichisoftenworsethanlackofwages.A)lazinessB)povertyC)idlenessD)inability

[试题]Computers will become more advanced and they will also become easier to use.Improved speed recognition will make the operation of a computer easier. Virtual reality（虚拟现实）， the technology of (71) with a computer using all of the human senses, will also

[名词解释] 装料 fuel loading