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单选题
（） is the production of pure water from sea water by evaporation and re-condensing.
A
Evaporation
B
Circulation
C
Condensation
D
Distillation
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更多 “单选题（） is the production of pure water from sea water by evaporation and re-condensing.A EvaporationB CirculationC CondensationD Distillation” 相关考题
考题
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．
考题
27． From the passage we know that fresh water doesn't come from________ ．A．riversB．lakesC．undergroundD．the sea
考题
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
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30． In order to solve the problem of water shortage，we' have to________．a． make use of sea water on the earthb． save as much fresh water as possiblec． reuse the water from large citiesd． stop people from，using watere． only use the 3% of the water on the earthA．a and eB．a，b and cC．b，c and dD．a，b and d
考题
From this selection we may conclude that the king's crown______.A. moved less water than pure gold of the same sizeB. moved more water than pure gold of the same weightC. moved more water than pure gold of the same sizeD. moved less water than pure gold of the same weight
考题
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
考题
When the water produced from most evaporator is supplied for drinking purpose, it must be treated to ensure it is biologically pure and _____.A.slightly acidicB.slightly alkalineC.no saltyD.slightly bitter
考题
Oil slick caused by spillage of oil from tanker ship is ______.A.a drop of oilB.the emulsion of oil at sea surfaceC.the weathered oilD.the oil floating on the surface of the sea water
考题
请阅读短文，完成此题。
When we analyze the salt salinity(盐溶度 ) of ocean waters, we find that it varies only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation. In this manner, the salinity is increased, since the salt stays behind. If this is carried to the extreme, of course, white salt would be left behind; this, by the way, is how much of the table salt we use is actually obtained.
The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of
high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by-evaporation, or decreased by the addition of fresh water by precipitation.
Normally, in hot regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas.
A third process by which salinity may be altered is associated with the formation and melting of sea ice. When seawater is frozen, the dissolved materials are left behind. In this manner, seawater directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared. Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water.
In the Weddell Sea, the densest water in the ocean is formed as a result of this freezing process, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portion of the oceans of the world.
The purpose of mentioning the Weddell Sea is__________.
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A．to give an example of cold-water salinity
B．to point out the location of deep waters
C．to make a comparison between hot-water salinity and cold-water salinity
D．to show that the water in the Weddell Sea varies in salinity from place to place
考题
It can be known from the passage that increase in the salinity of ocean water is caused by___________.A.melting of sea ice
B.precipitation
C.evaporation
D.supplement of salt
考题
The purpose of mentioning the Weddell Sea is___________.A.to give an example of cold-water salinity
B.to point out the location of deep waters
C.to make a comparison between hot-water salinity and cold-water salinity
D.to show that the water in the Weddell Sea varies in salinity from place to place
考题
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._________65A:Reducing B:Collecting C:Removing D:Casting
考题
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 things from the ocean,and we give to it.We take fishes from the ocean-millions of kilograms of fish,every year,to feed millions of people.______(46)We take minerals from the ocean.One way to get salt is to place seawater in a shallow basin and leave it until it evaporates.______(47) Much gold and silver drift dissolved in the waters of the sea,too.But the sea does not give them up by simple evaporation.Other gifts from the sea are pearls,sponges and seaweed.Pearls become jewelry.______(48)Seaweed becomes food of many kinds-even candy,and ice cream-as well as medicine.Believe it or not,fresh water is another gift from the sea.We cannot drink ocean water.______(49)But ocean water becomes fresh water when the salts are removed.In the future,we will find ourselves depending more and more on fresh water from the sea.The sea gives us food,fertilizer,minerals,water,and other gifts .What do we give the sea?Garbage.______(50)Huge as it is,the ocean cannot hold all the water we pour into it. Dumping 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.We are finally learning that if we destroy our sea,we might also destroy ourselves.Hopeful-ly,it is not too late.______(48)A: Natural sponges become cleaning aids.B: We pollute the ocean when we use it as a garbage dump.C: The area of the sea is becoming smaller and smaller.D: Along with salt,other minerals are left after evaporation.E: We even use their bones for fertilizer.F: Some of its contents may cause illness.
考题
淡水注入管（）A、fresh water filling pipeB、sea water filling pipeC、ballast water filling pipeD、bilge water filling pipe
考题
饮用水注入管（）A、fresh water filling pipeB、bilge water filling pipeC、drinking water filling pipeD、sea water filling pipe
考题
单选题Variations in the color of sea water from blue to green seem to be caused by high or low concentrations of salt.A
Changes B
Descriptions C
Measures D
Clarity
考题
单选题We use （） to distill fresh water from sea water.A
engineB
sea water pumpC
cylinder coolerD
fresh water generator
考题
单选题When distilling sea water the cooling water discharging from the distiller is fed back to evaporator as feed water （）.A
to decrease scale formationB
for better cooling effectC
for more economical purposeD
to raise vacuum
考题
单选题The fresh water generator produces fresh water （）.A
by cooling sea waterB
by heating sea waterC
by evaporation of sea waterD
by purifying sea water
考题
单选题The height of a light is measured from which reference plane?（）A
Mean low waterB
Mean high waterC
Average water levelD
Geographical sea level
考题
单选题The main propulsion diesel engine jacket water temperature rises above normal, with the raw water sea suction and the expansion tank water level being normalWhich of the following problems is most likely the cause?（）A
Faulty thermostatic bypass valveB
Eroded zinc pencils in the heat exchangerC
Steam formation in the expansion tankD
Excessive leakage from jacket water pump seal
考题
单选题Higher than normal jacket water temperatures occurring in all cylinders of a diesel engine can result from a/an （）.A
oil suction line restrictionB
correct amount of coolantC
cavitation erosion in the water jacketsD
clogged sea suction strainer
考题
单选题What should you apply to a fathometer reading to determine the depth of water?（）A
Subtract the draft of the vesselB
Add the draft of the vesselC
Subtract the sea water correctionD
Add the sea water correction
考题
单选题（） system is arranged to ensure that water can be drawn from any tank or the sea and discharged to any other tank or the sea as required to trim the vessel.A
The domestic waterB
Bilge waterC
Oil transferD
The ballast
考题
单选题When the water produced from most evaporator is supplied for drinking purpose, it must be treated to ensure it is biologically pure and （）.A
slightly acidicB
slightly alkalineC
no saltyD
slightly bitter
考题
单选题In a diesel engine jacket water cooler, with seawater cooling the fresh water, the（）A
sea water temperature must never be warmer than 40℃B
jacket water pressure should always be greater than the sea water pressureC
jacket water temperature must always be less than 60℃D
jacket water pressure must always be less than the sea water pressure
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