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In Death Valley, California, one of the hottest, most arid places in North America, there is much salt, and salt can damage rocks impressively. Inhabitants of areas elsewhere, where streets and highways are salted to control ice, are familiar with the resulting rust and deterioration on cars. That attests to the chemically corrosive nature of salt, but it is not the way salt destroys rocks. Salt breaks rocks apart principally by a process called crystal prying and wedging. This happens not by soaking the rocks in salt water, but by moistening their bottoms with salt water. Such conditions exist in many areas along the eastern edge of central Death Valley. There, salty water rises from the groundwater table by capillary action through tiny spaces in sediment until it reaches the surface.
Most stones have capillary passages that suck salt water from the wet ground. Death Valley provides an ultra-dry atmosphere and high daily temperatures, which promote evaporation and the formation of salt crystals along the cracks or other openings within stones. These crystals grow as long as salt water is available. Like tree roots breaking up a sidewalk, the growing crystals exert pressure on the rock and eventually pry the rock apart along planes of weakness, such as banding in metamorphic rocks, bedding in sedimentary rocks, or preexisting or incipient fractions, and along boundaries between individual mineral crystals or grains. Besides crystal growth, the expansion of halite crystals (the same as everyday table salt) by heating and of sulfates and similar salts by hydration can contribute additional stresses. A rock durable enough to have withstood natural condition for a very long time in other areas could probably be shattered into small pieces by salt weathering within a few generations.
The dominant salt in Death Valley is halite, or sodium chloride, but other salts, mostly carbonates and sulfates, also cause prying and wedging, as does ordinary ice. Weathering by a variety of salts, though often subtle, is a worldwide phenomenon. Not restricted to arid regions, intense salt weathering occurs mostly in salt-rich places like the seashore, near the large saline lakes in the Dry Valleys of Antarctica, and in desert sections of Australia, New Zealand, and central Asia.
What is the passage mainly about?
Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 39 to 46.
Because writing has become so important in our culture, we sometimes think of it as more real than speech. A little thought, however, will show why speech is primary and writing secondary to language. Human beings have been writing (as far as we can tell from surviving evidence) for at least 5000 years; but they have been talking for much longer, doubtless ever since there have been human beings.
When writing did develop, it was derived from and represented speech, although imperfectly. Even today there are spoken languages that have no written form. Furthermore, we all learn to talk well before we learn to write; any human child who is not severely handicapped physically or mentally will learn to talk: a normal human being cannot be prevented from doing so. On the other hand, it takes a special effort to learn to write. In the past many intelligent and useful members of society did not acquire the skill, and even today many who speak languages with writing systems never learn to read or write, while some who learn the rudiments of those skills do so only imperfectly.
To affirm the primacy of speech over writing is not, however, to disparage the latter. One advantage writing has over speech is that it is more permanent and makes possible the records that any civilization must have. Thus, if speaking makes us human, writing makes us civilized.
We sometimes think of writing as more real than speech because ______.
Culture is a word in common use with complex meanings, and is derived, like the term broadcasting, from the treatment and care of the soil and of what grows on it. It is directly related to cultivation and the adjectives cultural and cultured are part of the same verbal complex. A person of culture has identifiable attributes, among them a knowledge of and interest in the arts, literature, and music. Yet the word culture does not refer solely to such knowledge and interest nor, indeed, to education. At least from the 19th century onwards, under the influence of anthropologists and sociologists, the word culture has come to be used generally both in the singular and the plural (cultures) to refer to a whole way of life of people, including their customs, laws, conventions, and values. Distinctions have consequently been drawn between primitive and advanced culture and cultures, between elite and popular culture, between popular and mass culture, and most recently between national and global cultures. Distinctions have been drawn too between culture and civilization; the latter is a word derived not, like culture or agriculture, from the soil, but from the city. The two words are sometimes treated as synonymous. Yet this is misleading. While civilization and barbarism are pitted against each other in what seems to be a perpetual behavioural pattern, the use of the word culture has been strongly influenced by conceptions of evolution in the 19th century and of development in the 20th century. Cultures evolve or develop. They are not static. They have twists and turns. Styles change. So do fashions. There are cultural processes. What, for example, the word cultured means has changed substantially since the study of classical (that is, Greek and Roman) literature, philosophy, and history ceased in the 20th century to be central to school and university education. No single alternative focus emerged, although with computers has come electronic culture, affecting kinds of study, and most recently digital culture. As cultures express themselves in new forms not everything gets better or more civilized. The multiplicity of meanings attached to the word made and will make it difficult to define. There is no single, unproblematic definition, although many attempts have been made to establish one. The only non-problematic definitions go back to agricultural meaning (for example, cereal culture or strawberry culture) and medical meaning (for example, bacterial culture or penicillin culture). Since in anthropology and sociology we also acknowledge culture clashes, culture shock, and counter-culture, the range of reference is extremely wide.
It is stated in paragraph 1 that a cultured person ______.