It benefits the Earth by recycling water.
Its efficiency increases in areas with little rainfall.
It utilizes technology that is centuries old.
It results in lower utility payments.
第1题：
Compared to a constant pitch propeller, a controllable pitch propeller
A.more efficiently uses available engine power
B.operates at a lower efficiency at a fixed speed
C.produces the same torque at lower engine power
D.develops its rated power at a lower speed
第2题：
材料：
Spark erosion is caused by a voltage discharge between the main bearing and journal surface. The cause of the potential is the development of a galvanic element between the ship’s hull, sea water, and the propeller shaft/crankshaft.
The oil film acts as a dielectric. The puncture voltage in the bearing depends on the thickness of the oil film. With increasing engine ratings, the specific load in the main bearing is increased. his will reduce the oil film thickness, and enable the discharge to take place at a lower voltage level.
Since the hydrodynamic oil film thickness varies through a rotation cycle, the discharge will take place at roughly the same instant during each rotation cycle, i.e. when the film thickness is at its minimum. The roughening will accordingly be concentrated in certain areas on the journal surface. In the early stages, the roughened areas can resemble pitting erosion. but later, as the roughness increases, the small craters will scrape off and pick up white metal-hence the silvery white appearance.
Therefore, to ensure protection against spark erosion, the potential level must be kept at maximum 80 mV, which is feasible today with a high efficiency earthing device. If an earthing device is installed, its effectiveness must be checked regularly. Spark erosion is only observed in main bearings and main bearing journals.
问题：
According to the paragraph one, a voltage between the main bearing and journal surface is produced by______.
A.propeller rotation
B.leakage from M/E electric control unit
C.a galvanic element
D.friction between the main bearing and journal surface
______engine ratings increase, the hydrodynamic oil film between the main bearing and journal surface is______.A.The lower/thinner
B.The higher/the thicker
C.The lower/thicker
D.The higher/thinner
When will the spark erosion take place on the journal surface during each rotation cycle?A.when the film thickness is at its minimum
B.when the film thickness is at its maximum
C.when the engine is on its compression stroke
D.when the engine is on its exhaust stroke
During the engine room watch keeping, which equipment must be noted to ensure protection against spark erosion?A.the antifouling plant
B.the earthing device
C.the main engine electric heating coils
D.the shaft generator
请帮忙给出每个问题的正确答案和分析，谢谢！
第3题：
A .unpredictable future
B .being disabled by technology
C. turning the Earth into a huge dump by technology
D .abuse of technology
第4题：
What are two benefits for prospects, derived from the Cisco SBR methodology?（）
第5题：
第6题：
What is the main problem lied in the ship recycling industry?
A.It lies in the sustainable development
B.It is about how to recycle the ship as they can as possible
C.It is a big problem concerning environment, safety and health
D.The big problem is that ship-recycling will violate the regulations made by IMO
第7题：
Name one major advantage of transporting gas under refrigeration．
A.It increases its volume
B.It reduces its volume
C.It has less product per volume
D.None of the above
第8题：
Which of the following conditions is realized by the turbo-charging of a previously naturally aspirated diesel engine?
A.Ignition lag increases.
B.Lube oil system pressure increases.
C.Brake specific fuel consumption increases.
D.Mechanical efficiency increases.
第9题：
Which of the following best describe the customer benefits of change management in the operate phase？ Select exactly 1 answer（s） from the following：（）。
第10题：
What are the benefits of using TCAM technology in high-end routing products ？（）