相关考题
-
单项选择题
Glaciers are large masses of ice on land that show evidence of past or presentmovement. They grow by the gradual transformation of snow into glacier ice.A fresh snowfall is a fluffy mass of loosely packed snowflakes, small delicate iceconstals grown in the atmosphere. As the snow ages on the ground for weeks or months,(5) the crystals shrink and become more compact, and the whole mass becomes squeezedtogether into a more dense form, granular snow. As new snow falls and buries the oldersnow, the layers of granular snow further compact to form. firm, a much denser kind ofsnow, usually a year or more old, which has little pore space. Further burial and slowcementation―a process by which crystals become bound together in a mosaic of(10) intergrown ice crystals―finally produce solid glacial ice. In this process ofrecrystallization, the growth of new crystals at the expense of old ones, the percentage ofair is reduced from about 90 percent for snowflakes to less than 20 percent for glacier ice.The whole process may take as little as a few years, but more likely ten or twenty years orlonger. The snow is usually many meters deep by the time the lower layers art convened(15) into ice. In cold glaciers those formed in the coldest regions of the Earth, the entire mass of iceis at temperatures below the melting point and no free water exists. In temperate glaciers,the ice is at the melting point at every pressure level within the glacier, and free water ispresent as small drops or as larger accumulations in tunnels within or beneath the ice.(20) Formation of a glacier is complete when ice has accumulated to a thickness (and thusweight) sufficient to make it move slowly under pressure, in much the same way that solidrock deep within the Earth can change shape without breaking. Once that point is reached,the ice flows downhill, either as a tongue of ice filling a valley or as thick ice cap thatflows out in directions from the highest central area where the most snow accumulates.The up down leads to the eventual melting of ice. Which of the following does the passage mainly discuss?A．The effect of glaciers on climateB．Damage from glaciersC．Glacier formationD．The location of glaciers
A.
A
B.
The
C.
D.
(20)
E.
The
F.
G.The
H.Damage
I.Glacier
J.The -
单项选择题
What unusual or unique biological train led to the remarkable diversification andunchallenged success of the ants for ever 50 million years? The answer appears to bethat they were the first group of predatory ensocial insects that both lived and foragedprimarily in the soil and in rotting vegetation on the ground. Eusocial refers to a form(5) of insect society characterized by specialization of tasks and cooperative care of theyoung; it is rare among insects. Richly organized colonies of the land made possibleby eusociality enjoy several key advantages over solitary individuals. Under most circumstances groups of workers arc better able to forage for food anddefend the nest, because they can switch from individual to group response and back(10) again swiftly and according to need. When a food object or nest intruder is too large forone individual to handle, nestmates can be quickly assembled by alarm or recruitmentsignals. Equally important is the fact that the execution of multiple-step tasks isaccomplished in a series-parallel sequence. That is, individual ants can specialize inparticular steps, moving from one object (such as a larva to be fed) to another (a second(15) larva to be fed). They do not need to carry each task to completion from start to finish.for example, to check the larva first, then collect the food, then feed the larva. Hence, ifeach link in the chain has many workers in attendance, a senes directed at any particularobject is less likely to fail. Moreover, ants specializing in particular labor categoriestypically constitute a caste specialized by age or body form. or both. There has bees some(20) documentation of the superiority in performance and net energetic yield of various castesfor their modal tasks, although careful experimental studies are still relatively few.What makes ants unusual in the company of eusocial insects is the fact that they arethe only eusocial predators (predators are animals that capture and feed on other animals)occupying the soil and ground litter. The eusocial termites live in the same places as antsand also have wingless workers, but they feed almost exclusively on dead vegetation. Which of the following questions does the passage primarily answer?A．How do individual ants adapt to specialized tasks?B．What are the differences between social and solitary insects?C．Why are ants predators?D．Why have ants been able to thrive for such a long time?
A.
B.
for
C.
What
D.
E.How
F.What
G.Why
H.Why -
单项选择题
Composers today use a wider variety of sounds than ever before, including manythat were once considered undesirable noises. Composer Edgard Varese (1883-1965)called thus the 'liberation of sound...the right to make music with any and all sounds.'Electronic music, for example―made with the aid of computers, synthesizers, and(5) electronic instruments―may include sounds that in the past would not have beenconsdered musical Environmental sounds, such as thunder, and electronically generatedhisses and blips can be recorded, manipulated, and then incorporated into a musicalcomposition. But composers also draw novel sounds from voices and nonelectronicinstruments. Singers may be asked to scream, laugh, groan, sneeze, or to sing phonetic(10) sounds rather than words. Wind and string players may lap or scrape their instruments.A brass or woodwind player may hum while playing, to produce two pitches at once; a pianist may reach inside the piano to pluck a string and then run a metal blade along it. Inthe music of the Western world, the greatest expansion and experimentation have involvedpercussion instruments, which outnumber strings and winds in many recent compositions.(15) Traditional percussion instruments are struck with new types of beaters; and instrumentsthat used to be couriered unconvennonal in Western music―tom-toms, bongos,slapsticks, maracas―are widelv used. In the search for novel sounds, increased use has been made in Western music ofMicrotones. Non-Western music typically divides and interval between two pitches more(20) finely than Western music does, thereby producing a greter number of distinct tones,or micro tones, within the same interval. Composers such as Krzysztof Pmderecki createsound that borders on electronic noise through tone clusters―closely spaced tones playedtogether and heard as a mass, block, or band of sound. The directional aspect of sound hastaken on new importance as well Loudspeakers or groups of instruments may be placed(25) at opposite ends of the stage, in the balcony, or at the back and sides of the auditorium.Because standard music notation makes no provision for many of these innovations,recent music scores may contain graphlike diagrams, new note shapes and symbols, andnovel ways of arranging notation on the page. What does the passage mainly discuss?A．The use of nontraditional sounds in contemporary musicB．How sounds are produced electronicallyC．How standard musical notation has beer, adapted for nontraditional soundsD．Several composers who have experimented with the electronic production of sound
A...the
B.'
Electronic
C.
A
D.
(15)
E.
F.
Because
G.
H.The
I.How
J.How
K.Several
