题目内容
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Air is composed of ______ gas including hydrogen, oxygen and carbon dioxide.
A．varied
B．variant
C．variable
D．various
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更多“Air is composed of ______ gas including hydrogen, oxygen and carbon dioxide.A．variedB．vari”相关的问题
Air is composed of ______ gases including hydrogen, oxygen and carbon dioxide.
A. varied B. variant
C. variable D. various
A.0 km to 3.2 km is at or below 0°C, whereas the average air temperature at altitudes from 3.2 km to 6.0 km is above 0°C.
B.0 km to 3.2 km is at or below 0°C, whereas the average air temperature at altitudes from 6.0 km to 16.0 km is above 0°C.
C.0 km to 3.2 km is above 0°C, whereas the average air temperature at altitudes from 3.2 km to 6.0 km is at or below 0°C.
D.0 km to 3.2 km is above 0°C, whereas the average air temperature at altitudes from 6.0 km to 16.0 km is at or below 0°C.
Which of the following is TRUE according to the passage？
A．The volume of the atmosphere is four times that of the world's oceans.
B．The water in the oceans is the main source of rain and snow on land areas.
C．The atmosphere is mainly composed of the vapor carried over land by air currents.
D．The earth can not support the water in the atmosphere if it falls down onto the earth suddenly.
Which of the following is true according to the passage？
A．The volume of the atmosphere is four times that of the world's.
B．The water in the oceans is the main source of rain and snow on land areas.
C．The atmosphere is mainly composed of the vapor carded over land by air currents.
D．The earth cannot support the water in the atmosphere if it falls down onto the earth suddenly.
Section B
Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D.
听力原文： You may not realize that fog is simply a cloud that touches the ground. Like any cloud, it is composed of tiny droplets of water, or, in rare cases, of icy crystals that form. an ice fog. lce fogs usually occur only in extremely cold climates, because water droplets are so tiny they don't solidify until the air temperature is far below freezing, generally thirty degrees below zero Celsius or lower. These droplets are nearly spherical. The transparency of fog depends mainly on the concentration of droplets. The more droplets, the denser the fog is. Since water is eight hundred times denser than air, investigators were puzzled for a long time as to why the water particles in fog didn't simply fall to the ground, making the fog disappear. It turns out that droplets do fall at a predictable rate but in fog-creating conditions, they are either supported by rising air currents or continually replaced by new droplets condensing from water vapor in the air.
(27)
A．They both form. in large spherical masses.
B．They are both made of tiny water droplets.
C．They are both common only in cold climates.
D．They both change shape when temperatures vary.
No casual observer 'of a lichen would ever suspect that it was a composite of interacting life forms. This seemingly uncomplicated lichen is actually composed of a fungus and a colony of algae (or blue-green algae, which some scientists now consider to be bacteria). A few species even include all three of these diverse forms of life. A complete lichen is strikingly different from its separated partners in both appearance and biochemistry-many produce unique compounds which cannot be made by the component organisms alone.
Lichens grow in almost every natural habitat imaginable, from deserts to tropical rain forests-even on the backs of certain beetles in New Guinea, and i0side rocks (along with algae ) in the otherwise barren dry valleys of Antarctica.
Many species can tolerate extreme heat, cold. or dryness. Very few, however, can survive heavy air pollution, and many live only where the air is very clean. The disappearance of lichens from an area gives warning of a threatened environment.
The author states that lichens grow "as though designed to be ignored" because they are ______.
A．not totally understood by botanists
B．troublesome to collect for the purposes of study
C．uncomplicated in their internal structure
D．not easily noticed by observers
The actual amount of water in the plant at any one time, is only a very small part of what passes through it during its development. The processes of photosynthesis (光合作用), by which carbon dioxide and water are combined — in the presence of chlorophyll (叶绿素) and with energy derived from light — to form. sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaf. The leaf surface is not solid but contains great numbers of minute openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas — water vapor — to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10,000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80F, saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates.
A growing plant needs water for all of the following except ______ .
A．forming sugars
B．sustaining actively growing parts as well as woody stems
C．absorbing mineral elements
D．taking in carbon dioxide from the air
Part A
Directions: Read the following four texts. Answer the questions below each text by choosing A, B, C or D . Mark your answers on ANSWER SHEET 1.
Most growing plants contain much more water than all other materials combined. C. R. Barnes has suggested that it is as proper to term the plant a water structure as to call a house composed mainly of brick a brick building. Certain it is that all essential processes of plant growth and development occur in water. The mineral elements from the soil that arc usable by the plant must be dissolved in the soil solution before they can be taken into the root. They are carried to all parts of the growing plant and are built into essential plant materials while in a dissolved state. The carbon dioxide (CO2 ) from the air may enter the leaf as a gas but is dissolved in water in the leaf before it is combined with a part of the water to form. simple sugars --'the base material from which the plant body is mainly built. Actively growing plant parts are generally 75% to 90% water. Structural parts of plants, such as woody stems no longer actively growing, may have much less water than growing tissues.
The actual amount of water in the plant at ashy one time, however, is only a very small part of what passes through it during its development. The processes of photosynthesis, by which carbon dioxide and water are combined -- in the presence of chlorophyll and with energy derived from light- to form. sugars, require that carbon dioxide from the air enter the plant. This occurs mainly in the leaves. The leaf surface is not solid but contains great numbers of minute openings, through which the carbon dioxide enters. The same structure that permits the one gas to enter the leaf, however, permits another gas -- water vapor -- to be lost from it. Since carbon dioxide is present in the air only in trace quantities (3 to 4 parts in 10,000 parts of air) and water vapor is near saturation in the air spaces within the leaf (at 80°F, saturated air would contain about 186 parts of water vapor in 10,000 parts of air), the total amount of water vapor lost is many times the carbon dioxide intake. Actually, because of wind and other factors, the loss of water in proportion to carbon dioxide intake may be even greater than the relative concentrations of the two gases. Also, not all of the carbon dioxide that enters the leaf is synthesized into carbohydrates.
A growing plant needs water for all of the following EXCEPT ______.
A．forming sugars
B．sustaining woody stems
C．keeping green
D．producing carbon dioxide
Scientists have discovered that for the last 160,000 years, at least, there
has been a consistent relationship between the amount of carbon dioxide in the air
and the average temperature of the planet. The importance of carbon dioxide in
regulating the Earth's temperature was confirmed by scientists working in eastern
(5) Antarctica. Drilling down into a glacier, they extracted a mile-long cylinder of ice
from the hole. The glacier had formed as layer upon layer of snow accumulated year
after year. Thus drilling into the ice was tantamount to drilling back through time.
The deepest sections of the core are composed of water that fell as snow 160,000 years
ago. Scientists in Grenoble, France, fractured portions of the core and
temperature and of atmospheric
(10)measured the composition of ancient air released from bubbles in the ice. Instruments
were used to measure the ratio of certain isotopes in the frozen water to get an idea
of the prevailing atmospheric temperature at the time when that particular bit of
water became locked in the glacier. The result is a remarkable unbroken record of
(15)levels of carbon dioxide. Almost every time the chill of an ice age descended on the planet, carbon
dioxide levels dropped. When the global temperature dropped 9F (5℃), carbon dioxide levels
dropped to 190 parts per million or so. Generally, as each ice age ended and the Earth basked in a
warm interglacial period, carbon dioxide levels were around 280 parts per million. Through the
160,000 years of that ice
(20)record, the level of carbon dioxide in the atmosphere fluctuated between 190 and 280 parts per
million, but never rose much higher-until the industrial Revolution beginning in the eighteenth
century and continuing today. There is indirect evidence that the link between carbon dioxide levels
and global temperature change goes back much further than the glacial record. Carbon
(25)dioxide levels may have been much greater than the current concentration during the Carboniferous
period. 360 to 285 million years ago. The period was named for aprofusion of plant life whose
buried remains produced a large fraction of the coal deposits that am being brought to the surface
and burned today.
Which of the following does the passage mainly discuss？
A．Chemical causes of ice ages
B．Techniques for studying ancient layers of ice in glaciers
C．Evidence of a relationship between levels of carbon dioxide and global temperature
D．Effects of plant life on carbon dioxide levels in the atmosphere
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