单选题Sea water is not used directly as a coolant because of （）.Alow specific heatBhigh specific heatCcorrosive actionDhigh viscosity
单选题
Sea water is not used directly as a coolant because of （）.
A
low specific heat
B
high specific heat
C
corrosive action
D
high viscosity
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BThe world is not only hungry，it is also thirsty for water． this may seem strange to you，since nearly 75% of the earth is covered with water． But about 97% of this water is sea water．Man can only drink and use the other 3% fresh water that comes from rivers，lakes，under-ground and other places． And we cannot even use all of that，because some of this fresh water has been made dirty．At the moment，this small amount(数量) of fresh water is still enough for us． However，our need for water is getting greater and greater． Only if we take steps to solve this problem now，we can get away from a serious world water shortage later on． The people of the world cannot have an enjoyable life without enough clean water．On one hand we should stop wasting this little water of ours，on the other hand we should find ways to reuse it，but this has not been done widely．Today，in most large cities，water is used only once and it then returns to the sea or runs into underground places．lf we can make it clean again，it can be used once more just as if it were fresh from a spring．But even if large cities reuse its water，we still would not have enough in the future． Where．could we turn to next for water? To the ocean! How can we do to make use of this great a-mount of sea water? We can take the salt from the water to make it fresh．So if we take all these steps，we'll be in no danger of drying up!( )26． Why does the writer say that the world is thirsty for water?A． The amount of fresh water is really very small．B． The people of the world waste too much water．C． The people of the world have to drink a lot of water every day．D． There are too many people in the world needing water．
29． The writer thinks that people in large cities should __________ ．A． stop the used water from getting into undergroundB． only use the water from the riversC． make their used water clean againD． use as much sea water as possible
The sea looks very pretty when the sun is shining on it. It can be very rough when there is a strong wind. The sea is very big. It covers three quarters of the globe! The sea is also very deep in some places. There is one spot near the Philippines , where the sea is about 11 kilometers deep. The highest mountain in the world is about 9 kilometers high. If that mountain was put in the sea at that place, there would still be 3 kilometers of water above it! What a deep place! In most parts of the sea, there are plenty of fishes and plants. Some live near the top of the sea. Others live deep down. There are millions of tiny living things that float in the sea. Many fish live by eating them. The sea can be very cold. When the diver goes downwards, the sea becomes colder and colder. When the diver goes deeper, the water exerts greater pressure.1、There is one spot near the Philippines, where the sea is as deep as ( ).A、13 kilometersB、 9 kilometersC、 2 kilometersD、 11 kilometers2、There are millions of tiny living things that float in the sea, and( ).A、they live by eating fishB、they live by eating plantsC、they are good food for many fishD、they live by eating worms3、Which of the following statements is true? ( )A、When the diver dives under the sea, he gets colder and colder.B、When the diver sinks to the bottom, he is to be colder and colder.C、When the diver sinks in the sea, he will be rather cold.D、When the diver dives downward, the sea gets colder and colder.4、From the information given, why has the diver to wear a diving suit? ( )A、Because the diver is likely to be attacked by fish.B、 Because the water at great depths is very cold.C、 Because the salt water seems unsuitable for diver.D、 Because the pressure of water at great depths is immense ( 巨大的 ).
In a diesel engine closed freshwater cooling system, the amount of coolant flowing through the heat exchanger is controlled by the __.A.suction pressure regulatorB.thermostatic bypass valveC.sea water temperatureD.water level in the expansion tank
What is the most usual reason for the fresh water-sea water heat exchanger fouling in the sea side?A.lube oil sludge accumulating in itB.dirt and scale etc , formed on the surfacesC.deformation of the tubes and the shell or the platesD.lube oil leakage into sea-water side
Which of the following factors tends to increase scale formation on the saltwater side of a heat exchanger used in a diesel engine cooling water system?A.Baffle plates that have been bent during prior removalB.Leaks m the cooler tube nestC.Operating the engine while maintaining a high sea water outlet temperatureD.A punctured sea water strainer supplying cooling water to the heat exchanger
If a river flows directly into the sea，the baseline shall be a straight line across ______ between points on the low-water line of its banks．A.outer limit of the territorial seaB.limit of the territorial seaC.breadth of the territorial seaD.the mouth of the river
共用题干What We Take From and Give to the SeaAs long as we have been on earth,we have used the sea around us.We take from the ocean,and we give to it.We take fishes from the ocean-millions of kilograms of fish,every year,to________(51)millions of people.We even_______(52)their bones for fertilizer.We take minerals from the ocean.One way to get salt is to_______(53)seawater in shallow basin and leave it until it evaporates（蒸发）.Along with salt,other minerals are left_______(54)evaporation.Much gold and silver drift dissolved in the waters of the sea,too.But the sea does not give them_______(55)by simple evaporation.________(56)gifts from the sea are pearls , sponges（海绵）and seaweed.Pearls________(57)jewelry.Natural sponges become cleaning aids.Seaweed becomes______(58)of many kinds一even candy,and ice cream一as well as medicine.Believe it or not,fresh water is another_______(59)from the sea.We cannot drink ocean water.Some of its contents may______(60)illness.But ocean water becomes fresh water when the salts are ________(61).In the future,we will find ourselves．________(62)more and more onfresh water from the sea.The sea_______(63)us food,fertilizer,minerals,water,and other gifts.What do we give the sea?Garbage.We pollute the ocean_______(64)we use it as a garbage dump.Huge as it is,the ocean cannot hold all the water that we pour into it.________(65)garbage into the ocean is killing off sea life.Yet as the world population grows,we may need the sea and its gifts more than ever._________64A:if B:whenC:although D:because
After leaving the port, we used （）to clean the empty holds and decks.A、fresh waterB、sea waterC、both A and BD、ballast water
水泥涂料用于淡水舱和双层底舱。（）A、Primer is used for sea water tanks and double bottom tanks.B、Cement wash is used for fresh water tanks and double bottom tanks.C、Varnish is used for fresh water tanks and double bottom tanks.D、Bitumen is used for fresh water tanks and double bottom tanks.
单选题Which of the following factors tends to increase scale formation on the saltwater side of a heat exchanger used in a diesel engine cooling water system?（）ABaffle plates that have been bent during prior removalBLeaks in the cooler tube nestCOperating the engine while maintaining a high sea water outlet temperatureDA punctured sea water strainer supplying cooling water to the heat exchanger
单选题Because of the reduced （） in the distillation system, some of the sea water boils as it flows through the tubes of the evaporator.ApressureBtemperatureCdensityDvolume
单选题The fresh water generator produces fresh water （）.Aby cooling sea waterBby heating sea waterCby evaporation of sea waterDby purifying sea water
单选题（）is used to prevent the entry of sea water to the machinery space.AA special sealing glandBPropellerCTailshaftDSterntube bearing
单选题What should you apply to a fathometer reading to determine the depth of water?（）ASubtract the draft of the vesselBAdd the draft of the vesselCSubtract the sea water correctionDAdd the sea water correction
单选题In a central cooling system, used in some modem ships, sea water is supplied to cool （）which will circulate to other individual cooler, greatly reducing the corrosion problems.Afresh waterBsea waterCcooling oilDemulsion
单选题（） is used for cylinder and cylinder head, the salt water is used for cooling the lubricating oil, the fresh water in the coolers and the charging air in the air cooler.AThe fuel oilBThe lube oilCThe sea waterDThe fresh water
单选题A large, low-speed, main propulsion diesel engine uses sea water to directly cool the （）.Acylinder headsBexhaust valvesCscavenging airDinjectors
单选题Which of the following statements is correct concerning diesel engine cooling water systems?（）AEach engine must have its own engine driven cooling water pump capable of providing cooling for all ranges of operationBpropulsion engines with bores exceeding 200 mm are to be fitted with a means to display the cooling water temperature of each cylinderCAt least two independent sea suctions are to be provided for supplying water to the engine jackets or to the heat exchangersDSuitable strain are to be fitted between the circulating pumps and heat exchangers when sea water is used for direct cooling
单选题In a diesel engine jacket water cooler, with seawater cooling the fresh water, the（）Asea water temperature must never be warmer than 40℃Bjacket water pressure should always be greater than the sea water pressureCjacket water temperature must always be less than 60℃Djacket water pressure must always be less than the sea water pressure
单选题Because of the reduced （） in the vacuum boiling evaporator, some of the sea water boils as it flows through the tubes.AtemperatureBwater levelCpressureDrate of flow
单选题The pump used to send the bilge water into the oily water separator（）the mixture because this might create finer oil particles.Ashould agitateBshould not agitateCshould mix upDshould not add up
单选题According to the SOLAS convention, the bilge water system （）Amust connect the bilge well suction directlyBshould not pump out the water accumulated in the cargosCshould not used for emergency drainage in case of ship collisionDshould connect to the fire fighting system directly
单选题When water is used to fight a fire on board a ship，the effect of the weight of the water must be taken into account. How much sea water will increase the weight displacement by one ton?（）A64 cubic feetB35 cubic feetC100 gallonsD500 liters
单选题In a central cooling system, used in some modem ships, sea water is supplied to cool （）which will circulate to other individual cooler, greatly reducing the corrosion problems.Amain bearingsBsea waterCcooling oilDlower temperature fresh water
单选题Sea water is not directly used as a coolant for engines because of its （）.Alow specific heatBcorrosive actionChigh expenseDacid property