碳循环carbon cycle
碳循环carbon cycle
相关考题：
● Feasibility studies occur in which life cycle phase (s)?A ConceptualB Conceptual or DevelopmentC ExecutionD Preliminary planningE any life cycle phase
If all other conditions such as bore, stroke, speed, and mean effective pressures are equal, a two stroke/cycle diesel engine will develop approximatelyA.the same indicated horsepower as a four-stroke/cycle engineB.twice the indicated horsepower as a four-stroke/cycle engineC.one half the indicated horsepower as a four-stroke/cycle engineD.one power stroke for every two crankshaft revolutions
Theoretical perfect combustion in a diesel engine yields by-products of_____.A.aldehydes and carbon dioxideB.water vapor and carbon monoxideC.nitrogen and carbon monoxideD.water vapor and carbon dioxide
According to Harry Morrison, businesses .A．will benefit from cutting carbon emissionsB．should buy carbon allowances for shoppersC．are required to make up for their carbon emissionsD．have encouraged shoppers to take their custom elsewhere
共用题干第一篇Carbon FootprintHow often do you travel by plane?How much electricity do you use?These days everyone is worried about the size of their carbon footprint.In order to reduce global warming we need to make our carbon footprints smaller. But how much CO2 are we responsible for?A new book might be able to help.The Carbon Footprint of Everything looks at the different things we do and buy,and calculates the amount of CO2 all of the following created:the ingredients, the electricity used in the brewery，the equipment,the travel and commuting of the beer,and the packaging. It's amazing how many different things need to be included in each calculation.And it's frightening how much carbon dioxide everything produces.But all of this can help us decide which beer to drink.From Berners-Lee's calculations,it's clear that a pint(568ml)of locally-brewed beer has a smaller carbon footprint than a bottle of imported beer. This is because the imported beer has been transported from far away,and it uses more packaging. The local beer only produces 300g of CO2,but the imported beer produces 900g! So, one pint of local beer is better for the environment than three cans of cheap foreign lager from the supermarket.Berners-Lee has even calculated the carbon footprint of cycling to work.Nothing is more environmentally-friendly than riding a bike,surely?Well,it depends on what you've had to eat before. To ride a bike we need energy and for energy we need food.So if we eat a banana and then ride a kilometer and a half,our footprint is 65g of CO2.However,if we eat bacon before the bike ride,it's 200g. In fact,bananas are good in general because they don't need packaging,they can be transported by boat and they grow in natural sunlight.So,does this mean that cycling is bad for the environment?Absolutely not,for a start,if you cycle,you don't use your car,and the fewer cars on the road,the fewer traffic jams.And cars in traffic jams produce three times more CO2 than cars traveling at speed.Cycling also makes you healthy and less likely to go to a hospital. And hospitals have very big carbon footprints!So maybe it's time for us all to start making some changes.Pass me a banana and a pint of local beer,please.To make our carbon footprints smaller,we should often________.A:cycle to workB:drink more local beerC:calculate the amount of CO2D:buy cheap things from the supermarkets
One hertz is equal to one ( )A、cycle per centimeterB、cycle per meterC、cycle per secondD、cycle per eV
关于CYCLE93指令，（）（SIEMENS系统）。A、CYCLE93是切槽循环指令B、使用CYCLE93指令可以简化编程C、CYCLE93指令可实现断屑加工D、CYCLE93指令可用于切削圆锥面和圆弧面E、CYCLE93可用于径向沟槽的切削加工
关于CYCLE81指令，下面说法正确的是（）（SIEMENS系统）。A、CYCLE81是深孔钻循环指令B、使用CYCLE81指令可以简化编程C、CYCLE81指令执行间歇切削进给到孔的底部D、完成CYCLE81指令后刀具将返回到返回平面E、用CYCLE81指令钻孔切削到孔底后，刀具快速返回
关于CYCLE83指令，下面说法正确的是（）A、CYCLE83是深钻孔循环指令B、使用CYCLE83指令可以简化编程C、CYCLE83指令执行连续切削进给到孔的地步D、完成CYCLE83指令后刀具将返回到参考平面E、用CYCLE83指令钻孔切削到孔底后，刀具快速返回
单选题The size of the exhaust valve opening is （）Amost critical in a four-stroke cycle diesel engineBmost critical in a two-stroke/cycle diesel engineCmost critical in a four-stroke/cycle diesel engine if it is turbochargedDof equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine
单选题Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because （）Abearing pressure in a four-stroke/cycle acting single diesel engine is continually reversedBbearing pressure in a two-stroke/cycle single acting diesel engine is continually reversedCthe maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engineDtwo-stoke/cycle diesel engines require more complicated lubrication piping
单选题In diesel engines, the four basic events (intake, compression, power and exhaust) are performed once in （）.Atwo crankshaft revolutions in a two-stroke/cycle engineBtwo power strokes in a two-stroke/cycle engineCone power stroke in a two-stroke/cycle engineDtwo piston strokes in a two-stroke/cycle engine
单选题Which of the following statements is true regarding the installation of piston rings on two-stroke/cycle, diesel engines as compared to four-stroke/cycle, diesel engines?（）AIn a two-stroke/cycle engine, the rings run hotter, requiring the end gap to be greaterBSome provision must be made in a two-stroke/cycle engine to keep the rings from binding in the portsCNo gap is required to exist between the ends of the ring when cold in a two-stroke/cycle engine, but a small gap is required in a four-stoke/cycle engineDThe gaps should be staggered on either side of a piston in a two-stroke/cycle engine, while staggering is not necessary in a four-stroke/cycle engine
单选题If all other conditions such as bore, stroke, speed, and mean effective pressures are equal, a two-stroke/cycle diesel engine will develop approximately（）Athe same indicated horsepower as a four-stroke/cycle engineBtwice the indicated horsepower as a four-stroke/cycle engineCone half indicated horsepower as a four-stroke/cycle engineDone power stroke for every two crankshaft revolutions
单选题The combustion of larger molecules,（）have multiple carbon-carbon bonds involves a more complex series of reactions.AwhatBwhichCthatDwho
单选题Theoretical perfect combustion in a diesel engine yields by-products of （）.Aaldehydes and carbon dioxideBwater vapor and carbon monoxideCnitrogen and carbon monoxideDwater vapor and carbon dioxide
判断题Natural systems can reduce the amount of carbon dioxide in the atmosphere caused by carbon emissions.A对B错
单选题Why should you wear a self-contained breathing apparatus before entering the engine room after the fixed CO2 system has been discharged to combat a major fire?（）ABecause carbon dioxide dilutes the oxygen concentration in the atmosphere and may cause asphyxiationBBecause carbon dioxide breaks down in a fire into carbon monoxide which may cause blood poisoning in the person breathing this gasCBecause carbon dioxide is a colorless and odorless gas that becomes highly toxic in the presence of high temperatures and will quickly incapacitate a person exposed to this gasDThis action is unnecessary as carbon dioxide is not poisonous nor toxic but is a relatively harmless gas