题目内容
（请给出正确答案）
When is the sea ice at a minimum in a year？
A．In the middle of summer.
B．At the end of summer.
C．In the middle of September.
D．At the beginning of autumn.
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更多“When is the sea ice at a minim…”相关的问题
If the salinity(含盐量) of ocean waters is analyzed, it is found to vary 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--conversion of liquid water to water vapor. In this manner, the salinity is increased, since the salts staybehind. If this is carried to the extreme, of course, white crystals of salt would be left behind.
The opposite of evaporation is precipitation(降水), such as rain, by which water is added to the ocean. Here the ocean is being diluted(稀释) 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 or runoff(形成地表水部分的降水).
Normally, in tropical 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 whererivers 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, off Antarctica, the densest water in the oceans is formed as a result of this freezingprocess, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world.
Choose correct answers to the question: The best title of the passage can be “_____”.
A.Typical Oceans and Their Respective Features
B.The Causes of the Changes in Salinity of Ocean Water
C.Different Oceans Have Different Salinity
D.The Precipitation and Evaporation of Oceans
Which of the following processes will increase salinity of ocean waters？A.Evaporation.
B.Precipitation.
C.Melting.
D.Dilution.
According to this passage, the sea _ is likely to have the lowest salinity.A.in tropical areas
B.off Antarctica
C.of high rainfall
D.with abundant
The Weddell Sea _____.
A.is a good example of increased salinity in freezing sea water
B.is much larger in area than the Arctic oceans
C.has a much lower salinity now than ever
D.has the denser water in its upper parts
Coastal regions are mentioned as cases where _____.A.sea water is less salty because fresh water joins in
B.rivers carry industrial exhaust into sea
C.sea ice tends to melt more quickly than in the center of oceans
D.heavy water sinks to the deeper portions of the oceans
请帮忙给出每个问题的正确答案和分析，谢谢！
If the salinity(含盐量) of ocean waters is analyzed, it is round to vary 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—conversion of liquid water to water vapor. In this manner, the salinity is increased, since the sales stay behind. If this is carried to the extreme, of course, white crystals of 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 or runoff.
Normally, in tropical 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, off Antarctica, the densest water in the oceans 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 portions of the oceans of the world.
What does the passage mainly discuss？
A．The elements of salt.
B．The bodies of water of the world.
C．The many forms of ocean life.
D．The salinity of ocean water.
The Ice Age
Twenty thousand years ago, the earth was held in control by relentlessly (不宽容地) probing fingers of ice that drew power from frigid strongholds in the north and crept southwestward to bury forests, fields, and mountains. Landscapes that were violated by the slowly moving glaciers(冰川)would carry the scars of this advance far into the future. Temperatures dropped deeply, and land surfaces in many parts of the world were depressed by the unrelenting weight of the thrusting ice. At the same time, so much was drawn from the oceans to form. these huge glaciers that sea levels around the world fell by three hundred and fifty feet, and large areas of the continental shelf became dry land.
This period of the Earth's history had come to be called the Ice Age. In all, about eleven million square miles of land were covered with ice. The Ice Age terminated about fourteen thousand years ago when the ice sheets began to retreat. It took about seven thousand years for the ice to retreat to its present level.
There were no human beings on the earth during the Ice Age.
A．Right
B．Wrong
C．Not mentioned
The Ice Age
Twenty thousand years ago, the earth was held in control by relentlessly (不宽容地) probing fingers of ice that drew power from frigid strongholds in the north and crept southwestward to bury forests, fields, and mountains. Landscapes that were violated by the slowly moving glaciers(冰川 )would carry the scars of this advance far into the future. Temperatures dropped deeply, and land surfaces in many parts of the world were depressed by the unrelenting weight of the thrusting ice. At the same time, so much was drawn from the oceans to form. these huge glaciers that sea levels around the world fell by three hundred and fifty feet, and large areas of the continental shelf became dry land.
This period of the Earth's history had come to be called the Ice Age. In all, about eleven million square miles of land were covered with ice. The Ice Age terminated about fourteen thousand years ago when the ice sheets began to retreat. It took about seven thousand years for the ice to retreat to its present level.
There were no human beings on the earth during the Ice Age.
A．Right
B．Wrong
C．Not mentioned
What we take from and give to the sea
As 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 feed millions of people．________ （1）．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．________ （2）．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．________ （3）．Seaweed becomes food of many kinds—even candy，and ice cream—as well as medicine． Believe it or not．fresh water is anther gift from the sea．We eannot drink ocean water．________ （4）．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．________ （5）．Huge as it is，the ocean cannot hold all the water we pour into it，we may need the sea and its gifts more than ever．
We are finnaly learning that if we destroy our seas，we might also destroy ourselves．Hopefully，
it is not too late．
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 beoming 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．
第 11 题 请选择（1）处的最佳答案．
根据以下材料，回答题。
What We Take From and Give to the Sea
As 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. Hopefully， it is not too late.
请在第__（46）__处填上正确答案。 查看材料
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 anal 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.
What is the main idea of this passage？
A．The sea ice changes in Antarctic are different from those in Arctic.
B．Global warming influences the ice coverage at both poles.
C．Maps of sea ice movements around Antarctica and Arctic were made.
D．The melting of Arctic sea ice is faster than the expanding of Antarctic sea ice.
Hundreds of families dropped into the sea when______.
A．a strong ice storm tilted the ship.
B．the cruise ship sank all of a sudden.
C．the badly damaged ship leaned toward one side.
D．the frightened passengers fought desperately for lifeboats.
