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单选题
Many cast iron pistons are designed with heat dams, which serve to （）
A
keep piston crown temperatures elevated for smoother combustion
B
reduce the possibility of overheating the top compression ring
C
help retain the heat of compression to prevent ignition delay
D
help retain the heat of compression to prevent combustion knock
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更多 “单选题Many cast iron pistons are designed with heat dams, which serve to （）A keep piston crown temperatures elevated for smoother combustionB reduce the possibility of overheating the top compression ringC help retain the heat of compression to prevent ignition delayD help retain the heat of compression to prevent combustion knock” 相关考题
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第三篇Iron DeficienciesExperts have observed for years that endurance athletes,particularly females,frequently have iron deficiencies.Now a new study by a team of Purdue University researchers suggests that even moderate exercise may lead to reduced iron in the blood of women."We found that women who were normally inactive and then started a program of moderate exercise showed evidence of iron loss,"says Roseanne M.Lyle,associate professor at Purdue.Her study of 62 formerly inactive women who began exercising three times a week for six months was published in the journal Medicine & Science in Sports & Exercise."Women who consumed additional meat or took iron supplements were able to bounce back,"she notes."But the new exercisers who followed their normal diet showed a significant decrease in iron levels."Iron deficiency is very common among women in general,affecting one in four female teenagers and one in five women aged 18 to 45,respectively.But the ratio is even greater among active women,affecting up to 80 percent of female endurance athletes.This means,Lyle says,that"too many women ignore the amount of iron they take in."Women of childbearing age are at greatest risk,since their monthly bleeding is a major source of iron loss.Plus,many health-conscious women increase their risk by rejecting red meat,which contains the most easily absorbed form of iron.And because women often restrict their diet in an effort to control weight,they may not consume enough iron-rich food,and are liable to experience a deficiency."The average woman takes in only two thirds of the recommended daily allowance of iron," notes another expert."For a woman who already has a poor iron status,any additional iron loss from exercise may be enough to tip her over the edge into a more serious deficiency,"notes the expert. Exercise can result in iron loss through a variety of mechanisms.Some iron is lost in sweat,and,for unknown reasons,intense endurance exercise is sometimes associated with bleeding of the digestive system.The best sources of iron,and the only sources of the form of iron most readily absorbed by the body,are meat,chicken,and fish.Good sources of other forms of iron include dates,beans,and some leafy green vegetables.Who will have a significant decrease in iron levels?A:All the women.B:All the inactive women.C:Women who start to do moderate exercise and follow their normal diet.D:Women who start to do moderate exercise and consume additional meat or take iron supplements.
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第三篇Iron DeficienciesExperts have observed for years that endurance athletes,particularly females,frequently have iron deficiencies.Now a new study by a team of Purdue University researchers suggests that even moderate exercise may lead to reduced iron in the blood of women."We found that women who were normally inactive and then started a program of moderate exercise showed evidence of iron loss,"says Roseanne M.Lyle,associate professor at Purdue.Her study of 62 formerly inactive women who began exercising three times a week for six months was published in the journal Medicine & Science in Sports & Exercise."Women who consumed additional meat or took iron supplements were able to bounce back,"she notes."But the new exercisers who followed their normal diet showed a significant decrease in iron levels."Iron deficiency is very common among women in general,affecting one in four female teenagers and one in five women aged 18 to 45,respectively.But the ratio is even greater among active women,affecting up to 80 percent of female endurance athletes.This means,Lyle says,that"too many women ignore the amount of iron they take in."Women of childbearing age are at greatest risk,since their monthly bleeding is a major source of iron loss.Plus,many health-conscious women increase their risk by rejecting red meat,which contains the most easily absorbed form of iron.And because women often restrict their diet in an effort to control weight,they may not consume enough iron-rich food,and are liable to experience a deficiency."The average woman takes in only two thirds of the recommended daily allowance of iron," notes another expert."For a woman who already has a poor iron status,any additional iron loss from exercise may be enough to tip her over the edge into a more serious deficiency,"notes the expert. Exercise can result in iron loss through a variety of mechanisms.Some iron is lost in sweat,and,for unknown reasons,intense endurance exercise is sometimes associated with bleeding of the digestive system.The best sources of iron,and the only sources of the form of iron most readily absorbed by the body,are meat,chicken,and fish.Good sources of other forms of iron include dates,beans,and some leafy green vegetables.Which group of women will possibly have iron loss? A:one in four women aged 18 to 45.B:one in five female teenagers.C:80 percent of female endurance athletes.D:80 percent of active women.
考题
According to Paragraph 5，the EEOB’s decoration details( ) A.had almost no cast iron and plaster
B.hardly use of wood for fireproofing
C.are with the materials of granite，bronze，and glass
D.are with carved wood，oriental rugs，and stenciled wall patterns
考题
Which statements concerning casting and conversion are true？（） A、Conversion from int to long does not need a cast.B、Conversion from byte to short does not need a cast.C、Conversion from float to long does not need a cast.D、Conversion from short to char does not need a cast.E、Conversion from boolean to int using a cast is not possible.
考题
When comparing capacity-to-capacity， the IBM Rear Door Heat eXchanger helps provide more advantages than other available thermal environment solutions， usually at a fraction of the cost. Which of the following statements is NOT an advantage of the IBM Rear Door Heat eXchanger？ （）A、The IBM Rear Door Heat eXchanger may dramatically unburden existing AC units by cooling the air before it exhausts from the electronics into the hot aisle.B、The IBM Rear Door Heat eXchanger is a "hang， plug， and run" design so the units may be added quickly.C、The IBM Rear Door Heat eXchanger is equipped with two fans to help maintain water temperature at 18C （64.4F） and provide even air flow.D、The IBM Rear Door Heat eXchanger is designed to support a 42U rack.
考题
单选题The cast iron was melted and _____ into sand molds as soon as possible.A
regulatedB
relayedC
pouredD
oppressed
考题
单选题An advantage of aluminum pistons, when compared to cast iron pistons is （）.A
greater high temperature strengthB
better heat conductivityC
greater weight per cubic inchD
increased resistance to wear
考题
单选题The possibility of damage from operating a diesel engine at critical speeds is reduced by the use of（）.A
an isochronous governorB
elastic engine mountsC
a vibration damperD
a cast iron bed plate with good flexible qualities
考题
单选题Aluminum pistons have （） coefficient of thermal expansion compared with those of cast iron.A
higherB
lowerC
the sameD
none of the above
考题
单选题Cast irons weakness in tension and under shock loading limits its use to low pressure steam, air, oil and low speed water fittingsThe above sentence, most probably means （）.A
cast iron has weaknessB
cast iron can stand up shock loadingC
cast iron fittings are only suitable in low pressure situationD
east iron fittings are not suitable in low pressure situation
考题
单选题The cast iron（）for the cross-head are attached to the top section and seal off the crankcase.A
cylinder coverB
cross-head shoesC
guide-waysD
scavenging boxes
考题
单选题Increasing the compression ratio of a diesel engine while maintaining the designed rate of fuel flow will result in （）A
increased horsepowerB
reduced efficiencyC
increased heat lossD
lower cylinder pressures
考题
单选题Trunk type diesel engine pistons are effectively cooled when heat is（）A
radiated through the engine blockB
transferred to water cooled cylinder wallsC
conducted through the piston crownD
transferred to escaping exhaust gases
考题
多选题Which statements concerning casting and conversion are true？（）AConversion from int to long does not need a cast.BConversion from byte to short does not need a cast.CConversion from float to long does not need a cast.DConversion from short to char does not need a cast.EConversion from boolean to int using a cast is not possible.
考题
单选题Wrought iron has an inherent resistance to corrosion but is not to be had freely , its place has been taken by the cuprous alloysAccording to the above sentence , which of the following statements is true?（）A
Wrought iron can resist liquids flowB
It is difficult to attain the wrought ironC
Wrought iron should be combined with cuprous alloysD
The cuprous alloys have mere disadvantages than wrought iron
考题
单选题（） of the A-frames there is a strong cast iron frame called the scavenging air box.A
At the topB
At the bottomC
In the topD
In the bottom
考题
单选题At the top of the A-frames there is a strong cast iron frame called （）.A
cylinder linerB
cylinder coverC
the gear boxD
the scavenging box
考题
单选题On top of scavenging air box is mounted a strong cast iron frame for each cylinder known as（）A
cooling jacketB
cylinder linerC
piston crownD
cylinder cover
考题
单选题The cast iron guide-ways for （） are attached to the top section and seal off the crankcase.A
the connecting rodB
the cross-headC
the piston rodD
the air box
考题
单选题Trunk-type diesel engine pistons are most effectively cooled by heat（）A
conducted through the engine blockB
conducted to water cooled cylinder wallsC
conducted through the piston crownD
loss to escaping exhaust gases
考题
单选题Cast iron and gunmetal fittings are used freely in small sizes at moderate pressure; large fittings, those for high pressure and temperature are cast or mild steelIn the above sentence, the word “those” means （）.A
east iron firingsB
mild steel fittingsC
small fittingsD
large fittings
考题
单选题Cast iron pistons used in large propulsion diesel engines are constructed with （）A
not taper what so everB
the skirt being tapered and smaller than the crownC
the skirt being tapered and larger than the crownD
the crown being tapered and smaller than the skirt
考题
单选题"Cast iron has poor corrosion resistance to sea water, especially in the presence of bronzes" Implies（）.A
east iron is a cheap materialB
cast iron can pollute sea waterC
cast iron has mere corrosive than bronzes to sea waterD
cast iron is more corrosive to sea water when it meets with bronzes
考题
单选题An aluminum piston has lower inertia and higher coefficient of （） compared to that of cast iron.A
viscosityB
twisting momentsC
inertiaD
thermal expansion
考题
单选题For many years marine centrifuges were designed for （） operation, that is the machines were run for a period during which solids accumulated in the bowlThe machine was stopped when the accumulated solids began to impair its performance.A
purifyingB
batchC
long periodD
temporary
考题
单选题Cold clearances between the skirt of an aluminum piston and the cylinder liner is about （）A
twice as large as with a cast iron pistonB
the same size as with a cast iron pistonC
half as large as with a cast iron pistonD
the same size as the crown of an aluminum piston
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