later and closing earlier
later and closing later
earlier and closing earlier
earlier and closing later
第1题：
ENG VALVE CLOSED指哪个活门（）
第2题：
the engine is overloaded
the engine is cold
there is too much lube oil in the cylinders
the turbocharger is fouled
第3题：
A two stroke diesel engine exhaust temperature will be lower than a four stroke diesel engine of the same displacement because the _____. ① MEP is lower and the scavenging air is cooling the exhaust gases ② valve overlap in a four stroke
A.①
B.②
C.① and ②
D.Neither ① nor ② is correct
第4题：
excessively late injection timing for each cylinder
incorrectly adjusted intake valve timing
incorrectly adjusted fuel injector
incorrectly adjusted intake valve clearance
第5题：
liquid in the cylinder
low compression in the cylinder
high exhaust temperature
poor fuel penetration
第6题：
Worn intake valve guides
Pitted pre-combustion chambers
Loose valve tappets
High exhaust back pressure
第7题：
direct action of cam shaft
compressed air pressure
hydraulic “push rods”
direct action of the main piston moving down
第8题：
During the valve overlap period, the exhaust pressure of a turbocharged four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure ______.
A.effective cylinder scavenging and cooling
B.constant pressure from the turbochargers
C.cooler operation of the exhaust system
D.effective constant pressure for turbocharger operation
第9题：
(1) only is correct
(2) only is correct
both (1) and (2) are correct
Neither (1) or (2) are correct
第10题：
provide added wear protection against today’s corrosive quality of fuel
increase overall valve strength due to the high gas pressures
assist in dissipating heat due to the extreme operating temperatures
reduce the overall weight of the valve thus helping eliminate valve spring surge and hammering