题目内容
（请给出正确答案）
A．A week.
B．Two weeks.
C．A month.
D．A year.
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A、The Faerie Queene
B、The Shepherd's Calendar
C、Amoretti
D、Epithalamion
Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You should decide on the best choice.
If the salinity(含盐量) of ocean water 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 stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind. This, by the way, is the way 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(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(流量).
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.
How is the table salt we use obtained？
A．Subtract water from the ocean through evaporation.
B．Add water to the ocean through precipitation.
C．Dissolve materials in the ocean through heating.
D．Convert water vapor into liquid water.
A．The ocean salinity is lower in tropical regions.
B．The ocean salinity is higher in coastal regions where rivers flow into the sea.
C．The ocean salinity is higher in dry regions.
D．The ocean salinity is lower in regions with little precipitation.
A．It is sold with handled PalmPilot computers.
B．It has not enjoyed popularity in high school.
C．It is objected by many students.
D．It can work on a school's network central server.
A．Y
B．N
C．NG
A．Y
B．N
C．NG
A．Intense interaction.
B．Heated discussion.
C．Listening to a lecture.
D．Frequent questions from students.
A．Pessimistic.
B．Surprisingly good.
C．Opposite to people's expectation.
D．Unknown.
Biologists have known for some time that giraffes solve this problem by having 【C3】______ high blood pressure, about 【C4】______ that of human beings. But an international team of biologists began to 【C5】______ about this. If giraffes have such high blood pressure, they should have a 【C6】______ problem with swelling in their legs and feet. Why don't giraffes have swollen feet？
Giraffes should have 【C7】______ problem, too. Every time they bend heads 【C8】______ to drink, the blood should 【C9】______ to their heads and have a hard time 【C10】______ back up (when the head is down) to the heart. How come giraffes don't black out when they drink？
The answer to the 【C11】______ feet problem, the researchers found, is that giraffes have 【C12】______ the researchers call a "natural anti-gravity suit". It 【C13】______ out that the skin and other 【C14】______ in their legs and feet are 【C15】______ stiffer and tougher than those of other 【C16】______ . As a result, the blood vessels in the leg cannot swell.
Therefore, the blood has nowhere to go but back to the heart. What about blood rushing to the head 【C17】______ the giraffe bends down to drink？ The researchers found that the giraffe's jugular vein, which 【C18】______ blood from the head back to the heart, has lots of one-way valves in it. In the giraffe's neck, there are lots of muscles that flex and relax repeatedly as the animal moves its head and sucks 【C19】______ drinking water. By squeezing the valved jugular vein, they 【C20】______ blood moving back to the heart even while the animal is drinking.
【C1】
A．bring
B．produce
C．transfer
D．pump
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