1995年08月语法题
1. According to the third law of (B) The influence of Louis Armstrong
thermodynamics, _____ possible is –273.16 (C) The music of Louis Armstrong
degrees centigrade. (D) Louis Armstrong’s talent
(A) that temperature is lowest
(B) the temperature is lower 8. Before every presidential election in the United
(C) lowest temperature States, the statisticians try to guess the proportion of
(D) the lowest temperature. the population that __ for each candidate.
(A) are voted
2. After the First World War, the author Anais Nin (B) voting
became interested in the art movement known as (C) to be voted
Surrealism and in psychoanalysis, both __ her (D) will vote
novels and shorts stories.
(A) in which the influence 9. _____at a river ford on the Donner Pass route
(B) of which influenced to California, the city of Reno grew as bridges
(C) to have influence and railroad were built.
(D) its influence in (A) Settle
(B) To settle
3. Muskrats generally _____ close to the edge of a (C) It was settling
bog, where their favorite plant foods grow (D) Having been settled
plentifully. 10. The air inside a house or office building
(A) staying often has higher concentrations of contaminants
(B) they are staying _____ heavily polluted outside air.
(C) stay (A) than does
(D) to stay there (B) more
(C) as some that are
4. Oliver Ellsworth,____ of the United States (D) like of
Supreme Court, was the author of the bill that
established the federal court system. 11. The decimal numeral system is one of the
(A) he was the third chief justice _____ ways of expressing numbers.
(B) the third chief justice was (A) useful most world’s
(C) who the third chief justice (B) world’s most useful
(D) the third chief justice (C) useful world’s most
(D) most world’s useful
5. _____ Colonial period the great majority of
Connecticut’s settlers came from England. 12. Emily Dickinson’s garden was a place __ great
(A) Since inspiration for her poems.
(B) The time (A) that she drew
(C) During the (B) by drawing her
(D) It was (C) from which she drew
(D) drawn from which
6. A politician can make a legislative proposal 13. The mountains surrounding Los Angeles
more _____ by giving specific examples of effectively shield the city from the hot, dry winds of
what its effect will be. the Mojave Desert, __ the circulation of air.
(A) to understanding (A) but they also prevent
(B) understandably (B) also prevented by them
(C) understandable (C) and also to prevent
(D) when understood (D) and also preventing
7. Playing the trumpet with dazzling 14. Not only _____ to determine the depth of
originality,___ dominated jazz for 20 years. the ocean floor, but it is also used to locate oil.
(A) Louis Armstrong (A) to use seismology
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(B) is seismology used (A) in others drought
(C) seismology is used (B) droughts are others
(D) using seismology (C) while other droughts
(D) others in drought
15. Nebraska has floods in some years, _____.
16. Pop Art was a movement of the 1950’s and 1960’s whom imagery was based on readily
recognized American products and people.
17. Because the tachinid fly is a parasite of harmful insects, much species have been imported into
the United States to combat insect pests.
18. All almost the electricity for industrial use comes from large generators driven by steam
turbines.
19. The Egyptians first discovered that drying fruit preserved it, made it sweeter, and improvement
its flavor.
20. During his twelve year there, Ellsi Marsalis turned the New Orleans Center for the Creative Arts
into a rich training place for future jazz stars.
21. Algebra is the branch of mathematics concerned with operations on sets of numbers or other
elements that are often represented at symbols.
22. As her focus changed, the love poetry that Edna St. Vincent Millay produced in the 1920’s increasing gave
way to poetry dealing with social injustice.
23. When a pearl is cut in half and examined under a microscope, but its layers can be seen.
24. A conductor uses signals and gesture to let the musicians to know when to play various parts of
a composition.
25. If a glass lizard loses its tails, a new one grows to replace it.
26. Many of the recording instruments used in vary branches of science are kymographs.
27. It was near end of prehistoric times that the first wheeled vehicles appeared.
28. Martin Luther King Jr.’s magnificent speaking ability enabling him to effectively express the
demands for social justice for Black Americans.
29. Designers of athletic footwear finely tune each category of shoe to its particularly activity by
studying human motion and physiology.
30. Gothic Revival architecture has several basis characteristics that distinguish it from other
nineteenth-century architectural styles.
31. Since rats are destructive and may carry disease, therefore many cities try to exterminate them.
32. In the United States among 60 percent of the space on the pages of newspapers is reserved for
advertising.
33. Recently in the automobile industry, multinational companies have developed to the point
where such few cars can be described as having been made entirely in one country.
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34. Scientists believe that by altering the genetic composition of plants it is possible to develop
specimens that are resisting to disease and have increased food value.
35. The purpose of traveler’s checks is to protect travelers from theft and accidental lost of money.
36. The early periods of aviation in the United States was marked by exhibition flights made by individual fliers
or by teams of performers at country fairs.
37. The American anarchist Emma Goldman infused her spirited lectures, publishes, and
demonstrations with a passionate belief in the freedom of the individual.
38. Being the biggest expanse of brackish water in the world, the Baltic Sea is of special interesting
to scientists.
39. The main advertising media include direct mail, radio, television, magazines, and newspaper.
40. While studying the chemistry of human body, Dr. Rosalyn Yalow won a Nobel Prize for the
research she conducted on the role of hormones.
Question 1-9
The ocean bottom – a region nearly 2.5 times greater than the total land area of the Earth – is
a vast frontier that even today is largely unexplored and uncharted. Until about a century ago, the
deep – ocean floor was completely inaccessible, hidden beneath waters averaging over (5) 3,6000
meters deep. Totally without light and subjected to intense pressures hundreds of times greater than
at the Earth's surface, the deep – ocean bottom is a hostile environment to humans, in some ways as
forbidding and remote as the void of outer space.
Although researchers have taken samples of deep – ocean rocks and (10) sediments for over a
century, the first detailed global investigation of the ocean bottom did not actually start until 1968,
with the beginning of the National Science Foundation's Deep Sea Drilling Project (DSDP). Using
techniques first developed for the offshore oil and gas industry, the DSDP's drill ship, the Glomar
Challenger, was able to maintain a steady (15) position on the ocean's surface and drill in very deep
waters, extracting samples of sediments and rock from the ocean floor.
The Glomar Challenger completed 96 voyages in a 15 – year research program that ended in
November 1983. During this time, the vessel logged 600,000 kilometers and took almost 20,000
core samples of seabed (20)sediments and rocks at 624 drilling sites around the world. The Glomar
Challenger's core samples have allowed geologists to reconstruct what the planet looked like
hundreds of millions of years ago and to calculate what it will probably look like millions of years
in the future. Today, largely on the strength of evidence gathered during the Glomar (25)
Challenger's voyages, nearly all earth scientists agree on the theories of plate tectonics and
continental drift that explain many of the geological processes that shape the Earth.
The cores of sediment drilled by the Glomar Challenger have also yielded information critical
to understanding the world's past climates. (30)Deep – ocean sediments provide a climatic record
stretching back hundreds of millions of years, because they are largely isolated from the mechanical
erosion and the intense chemical and biological activity that rapidly destroy much land – based
evidence of past climates. This record has already provided insights into the patterns and causes of
past climatic change – information that may be used to predict future climates.
1. The author refers to the ocean bottom as a "frontier"
in line 2 because it 2. The word "inaccessible" in line 4 is closest in
(A) is not a popular area for scientific research meaning to
(B) contains a wide variety of life forms (A) unrecognizable
(C) attracts courageous explorers (B) unreachable
(D) is an unknown territory (C) unusable
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(D) unsafe (B) the first extensive exploration of the ocean
bottom
3. The author mentions outer space in line 8 (C) composed of geologists from all over the
because world
(A) the Earth's climate millions of years ago was (D) funded entirely by the gas and oil industry
similar to conditions in outer space
(B) it is similar to the ocean floor in being alien to the 7. The word "strength" in line 24 is closest in
human environment meaning to
(C) rock formations in outer space are similar to those (A) basis
found on the ocean floor (B) purpose
(D) techniques used by scientists to explore outer (C) discovery
space were similar to those used in ocean (D) endurance
exploration
4. Which of the following is true of the Glomar 8. The word "they" in line 31 refers to
Challenger? (A) years
(A) It is a type of submarine. (B) climates
(B) It is an ongoing project. (C) sediments
(C) It has gone on over 100 voyages. (D) cores
(D) It made its first DSDP voyage in 1968.
9. Which of the following is NOT mentioned in the
5. The word "extracting" in line 16 is closest in passage as being a result of the Deep Sea Drilling
meaning to Project?
(A) breaking (A) Geologists were able to determine the Earth's
(B) locating appearance hundreds of millions of years ago.
(C) removing (B) Two geological theories became more
(D) analyzing widely accepted by scientists.
(C) Information was revealed about the Earth's
6. The Deep Sea Drilling Project was significant past climatic changes.
because it was (D) Geologists observed forms of marine life
(A) an attempt to find new sources of oil and gas never before seen.
Questions 10-21
Basic to any understanding of Canada in 20 years after the Second World War is the country's
impressive population growth. For every three Canadians in 1945, there were over five in 1996. In
September 1966 Canada's population passed the 20 million mark. Most of this surging (5)growth
came from natural increase. The depression of the 1930's and the war had held back marriages and
the catching – up process began after 1945. The baby boom continued through the decade of the
1950's, producing a population increase of nearly fifteen percent in the five years from 1951 to
1956. This rate of increase had been exceeded only once (10)before in Canada's history, in the
decade before 1911, when the prairies were being settled. Undoubtedly, the good economic
conditions of the 1950's supported a growth in the population, but the expansion also derived from a
trend toward earlier marriages and an increase in the average size of families. In 1957 the Canadian
birth rate stood at 28 per (15) thousand, one of the highest in the world.
After the peak year of 1957, the birth rate in Canada began to decline. It continued falling
until in 1966 it stood at the lowest level in 25 years. Partly this decline reflected the low level of
births during the depression and the war, but it was also caused by changes in Canadian society.
Young (20) people were staying at school longer, more women were working, young married
couples were buying automobiles or houses before starting families, rising living standards were
cutting down the size of families. It appeared that Canada was once more falling in step with the
trend toward smaller families that had occurred all through the Western world since the (25) time of
the Industrial Revolution.
Although the growth in Canada's population has slowed down by 1966 (the increase in the
first half of the 1960's was only nine percent). Another large population wave was coming over the
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horizon. It would be composed of the children of the children who were born during the period of
the high (30) birth rate prior to 1957.
10. What does the passage mainly discuss? 16. The word "peak" in line 16 is closest in
(A) Educational changes in Canadian society. meaning to
(B) Canada during the Second World War (A) pointed
(C) Population trends in postwar Canada (B) dismal
(D) Standards of living in Canada (C) mountain
(D) maximum
11. According to the passage, when did Canada's 17. When was the birth rate in Canada at its lowest
baby boom begin? postwar level?
(A) In the decade after 1911 (A) 1966
(B) After 1945 (B) 1957
(C) During the depression of the 1930's (C) 1956
(D) In 1966 (D) 1951
12. The word "five" in line 3 refers to 18. The author mentions all of the following as causes of
(A) Canadians declines in population growth after 1957 EXCEPT
(B) Years (A) people being better educated
(C) Decades (B) people getting married earlier
(D) Marriages (C) better standards of living
(D) couples buying houses
13. The word "surging" in line 4 is closest in
meaning to 19. It can be inferred from the passage that before the
(A) new industrial Revolution
(B) extra (A) families were larger
(C) accelerating (B) population statistic were unreliable
(D) surprising (C) the population grew steadily
(D) economic conditions were bad
14. The author suggests that in Canada during
the 1950's 20. The word "It" in line 28 refers to
(A) the urban population decreased rapidly (A) horizon
(B) fewer people married (B) population wave
(C) economic conditions were poor (C) nine percent
(D) the birth rate was very high (D) first half
15. The word "trend" in line 13 is closest in 21. The phrase "prior to" in line 30 is closest in
meaning to meaning to
(A) tendency (A) behind
(B) aim (B) Since
(C) growth (C) During
(D) directive (D) Preceding
Questions 22-30
Are organically grown foods the best food choices? The advantages claimed for such foods
over conventionally grown and marketed food products are now being debated. Advocates of
organic foods – a term whose meaning varies greatly – frequently proclaim that such products are
(5) safer and more nutritious than others.
The growing interest of consumers in the safety and more nutritional quality of the typical
North American diet is a welcome development. However, much of this interest has been sparked
by sweeping claims that the food supply is unsafe or in adequate in meeting nutritional needs.
8
(10)Although most of these claims are not supported by scientific evidence, the preponderance of
written material advancing such claims makes it difficult for the general public to separate fact from
fiction. As a result, claims that eating a diet consisting entirely of organically grown foods prevents
or cures disease or provides other benefits to health have (15) become widely publicized and form
the basis for folklore.
Almost daily the public is besieged by claims for "no-aging" diets, new vitamins, and other
wonder foods. There are numerous unsubstantiated reports that natural vitamins are superior to
synthetic ones, that fertilized eggs are nutritionally superior to unfertilized eggs, that (20)untreated
grains are better than fumigated grains and the like.
One thing that most organically grown food products seem to have in common is that they
cost more than conventionally grown foods. But in many cases consumers are misled if they believe
organic foods can maintain health and provide better nutritional quality than conventionally (25)
grown foods. So there is real cause for concern if consumers, particularly those with limited
incomes, distrust the regular food and buy and buy only expensive organic foods instead.
22. The world "Advocates" in line 3 is closest in (A) improve
meaning to which of the following? (B) monitor
(C) preserve
(A) Proponents (D) restore
(B) Merchants 28. The author implies that there is cause for
(C) Inspectors concern if consumers with limited incomes buy
(D) Consumers organic foods instead of conventionally grown
23. In line 5, the word "others" refers to foods because
(A) advantages (A) organic foods can be more expensive but
(B) advocates are often no better than conventionally grown
(C) organic foods foods
(D) products (B) many organic foods are actually less nutritious
than similar conventionally grown foods
24. The "welcome development" mentioned in line (C) conventionally grown foods are more
7 is an increase in readily available than organic foods
(A) interest in food safety and nutritional quality (D) too many farmers will stop using
of the typical North American diet conventional methods to grow food crops.
(B) the nutritional quality of the typical North
American diet 29. According to the last paragraph, consumers
(C) the amount of healthy food grown in North who believe that organic foods are better than
America conventionally grown foods are often
(D) the number of consumers in North America (A) careless
(B) mistaken
25. According to the first paragraph, which of the (C) thrifty
following is true about the term "organic foods"? (D) wealthy
(A) It is accepted by most nutritionists.
(B) It has been used only in recent years. 30. What is the author's attitude toward the
(C) It has no fixed meaning. claims made by advocates of health foods?
(D) It is seldom used by consumers. (A) Very enthusiastic
(B) Somewhat favorable
26. The word "unsubstantiated" in line 18 is (C) Neutral
closest in meaning to (D) Skeptical
(A) unbelievable
(B) uncontested
(C) unpopular
(D) unverified
27. The word "maintain" in line 24 is closest in
meaning to
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Questions 31-40
There are many theories about the beginning of drama in ancient Greece. The one most
widely accepted today is based on the assumption that drama evolved from ritual. The argument for
this view goes as follows. In the beginning, human beings viewed (5) the natural forces of the
world, even the seasonal changes, as unpredictable, and they sought through various means, to
control these unknown and feared powers. Those measures which appeared to bring the desired
results were then retained and repeated until they hardened into fixed rituals. Eventually stories (10)
arose which explained or veiled the mysteries of the rites. As time passed some rituals were
abandoned, but the stories, later called myths, persisted and provided material for art and drama.
Those who believe that drama evolved out of ritual also argue that those rites contained the
seed of theater because music, dance, (15) masks, and costumes were almost always used.
Furthermore, a suitable site had to be provided for performances, and when the entire community
did not participate, a clear division was usually made between the "acting area" and the
"auditorium." In addition, there were performers, and since considerable importance was (20)
attached to avoiding mistakes in the enactment of rites, religious leaders usually assumed that task.
Wearing masks and costumes, they often impersonated other people, animals, or supernatural
beings, and mimed the desired effect - success in hunt or battle, the coming rain, the revival of the
Sun - as an actor (25) might. Eventually such dramatic representations were separated from
religious activities.
Another theory traces the theater's origin from the human interest in storytelling. According to
this view, tales (about the hunt, war, or other feats) are gradually elaborated, at first through (30)the
use of impersonation, action, and dialogue by a narrator and then through the assumption of each of
the roles by a different person. A closely related theory traces theater to those dances that are
primarily rhythmical and gymnastic or that are imitations of animal movements and sounds.
31. What does the passage many discuss? 35. The word "considerable" in line 19 is closest
(A) The origins of theater in meaning to
(B) The role of ritual in modern dance (A) thoughtful
(C) The importance of storytelling (B) substantial
(D) The variety of early religious activities. (C) relational
(D) ceremonial
32. The word "they" in line 6 refers to
(A) seasonal changes 36. The word "enactment" in line 20 is closest
(B) natural forces in meaning to
(C) theories (A) establishment
(D) human beings (B) performance
(C) authorization
33. What aspect of drama does the author (D) season
discuss in the first paragraph?
(A) The reason drams is often unpredictable 37. The word "they" in line 22 refers to
(B) The seasons in which dramas were (A) mistakes
performed (B) costumes
(C) The connection between myths and (C) animals
dramatic plots (D) performers
(D) The importance of costumes in early drama
38. According to the passage, what is the main
34. Which of the following is NOT mentioned difference between ritual and drama?
as a common element of theater and ritual? (A) Ritual uses music whereas drama does not.
(A) Dance (B) Ritual is shorter than drama.
(B) Costumes (C) Ritual requires fewer performers than
(C) Music drama.
(D) Magic (D) Ritual has a religious purpose and drama
does not.
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39. The passage supports which of the
following statements? 40. Where in the passage does the author
(A) No one really knows how the theater began discuss the separation of the stage and the
(B) Myths are no longer represented audience?
dramatically. (A) Lines 10-12
(C) Storytelling is an important part of dance (B) Lines 15-18
(D) Dramatic activities require the use of (C) Lines 25-26
costumes. (D) Lines 28-32
Questions 41-50
Staggering tasks confronted the people of the united States, North and South, when the Civil
war ended. About a million and a half soldiers from both sides had to be demobilized, readjusted to
civilian life, and reabsorbed by the devastated economy. Civil government also had to be (5) put
back on a peacetime basis and interference from the military had to be stopped.
The desperate plight of the South has eclipsed the fact that reconstruction had to be
undertaken also in the North, though less spectacularly. Industries had to adjust to peacetime
conditions, factories (10) had to be retooled for civilian needs.
Financial problems loomed large in both the North and the South. The national debt had shot
up from a modest $65 million in 1861, the year the ear started to nearly $3 billion in 1865, the year
the war ended. This was a colossal sum for those days but one that a prudent government could pay.
(15) At the same time, war taxes had to be reduced to less burdensome levels.
Physical devastation caused by invading armies, chiefly in the South and border states, had to
be repaired. This herculean task was ultimately completed, but with discouraging slowness.
(20) Other important questions needed answering. What would be the future of the four million
black people who were freed from slavery? On what basis were the Southern states to be brought
back into the Union?
What of the Southern leaders, all of whom were liable to charges of treason? One of these
leaders, Jefferson Davis, President of the Southern (25) Confederacy, was the subject of an insulting
popular Northern song, "Hang Jeff Davis from a Sour Apple Tree." And even children sang it.
Davis was temporarily chained in his prison cell during the early days of his two-year
imprisonment. But he and the other Southern leaders were finally released, partly because it was
unlikely that a jury from Virginia, a (30) Southern Confederate state, would convict them. All the
leaders were finally pardoned by President Johnson in 1868 in an effort to help reconstruction
efforts proceed with as little bitterness as possible.
41. What does the passage mainly discuss?
(A) Wartime expenditures 44. According to the passage, which of the following
(B) Problems facing the United States after the war statements about the damage in the South is correct?
(C) Methods of repairing the damage caused by the (A) It was worse than in the North.
war (B) The cost was less than expected
(D) The results of government efforts to revive the (C) It was centered in the border states.
economy (D) It was remedied rather quickly.
42. The word "Staggering" in line 1 is closest in 45. The passage refers to all of the following
meaning to as necessary steps following the Civil War
(A) specialized EXCEPT
(B) confusing (A) helping soldiers readjust
(C) various (B) restructuring industry
(D) overwhelming (C) returning government to normal
43. The word "devastated" in line 4 is closest in (D) increasing taxes
meaning to
(A) developing 46. The word "task" in line 18 refers to
(B) ruined (A) raising the tax level
(C) complicated (B) sensible financial choices
(D) fragile (C) worse decisions about former slaves
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(D) reconstruction of damaged areas (D) All of the Virginia military leaders had
been put in chains.
47. Why does the author mention a popular song
in lines 25-26? 49. The word "them" in line 30 refers to
(A) To give attitude towards the South (A) charges
(B) To illustrate the Northern love of music (B) leaders
(C) To emphasize the cultural differences between the (C) days
North and the South (D) irons
(D) To compare the Northern and Southern
presidents 50. It can be inferred from the passage that
President Johnson pardoned the Southern leaders
48. Which of the following can be inferred from in order to
the phrase "it was unlikely that a jury from (A) raise money for the North
Virginia, a Southern Confederate state, would (B) repair the physical damage in the South
convict them" (lines 29-30)? (C) prevent Northern leaders from punishing
(A) Virginians felt betrayed by Jefferson Davis more Southerners
(B) A popular song insulted Virginians (D) help the nation recover from the war.
(C) Virginians were loyal to their leaders
1995年10月语法题
1.___the demands of aerospace, medicine, and agriculture, 5. ___ no real boundary to the part of the
engineers are creatingexotic new metallic substances. ocean referred to as a “deep” because of
(A) Meet changing water levels and movement in the
(B) Being met are sea floor.
(C) To meet (A) It is
(D) They are meeting (B) To be
(C) Being
2. _____ James A. Bland, “Carry Me Back to (D) There is
Old Virginny” was adapted as the state song
of Virginia in 1940. 6. Unlike moderate antislavery advocates,
(A) Was written by abolitionists _____ an immediate end to
(B) His writing was slavery.
(C) He wrote the (A) demanded
(D) Written by (B) they demand
(C) that they demanded
3. Mary Garden, _____ the early 1900’s, was (D) in that they demand
considered one of the best singing actresses of
her time. 7. A few animals sometimes fool their
(A) a soprano was popular enemies _____ to be dead.
(B) in a popular soprano (A) appear
(C) was a popular soprano (B) to appear
(D) a popular soprano in (C) by appearing
4. In the realm of psychological theory, (D) to be appearing
Margaret F. Washburn was a dualist __ that
motor phenomena have an essential role in 8. _____ of the mourning dove is made only
psychology. by the male.
(A) who she believed (A) That the sad cooing call
(B) who believed (B) The sad cooing call
(C) believed (C) Is the sad cooing call
(D) who did she believe (D) The cooing call is sad.
12
9. The work of painters in the United States (A) as prevalent
during the early twentieth century is noted for (B) that prevalent
_____ as well as telling stories. (C) so prevalent as
(A) it is representing of images (D) prevalent than
(B) which images representing
(C) the images representing 13. Most natural ports are located where the
(D) representing images shoreline is irregular and _____.
(A) deep water
10. Abraham Lincoln insisted that _____ not just (B) is the water deep
on mere opinion but on moral purpose. (C) the water is deep
(A) to base democracy (D) there is the deep water
(B) for democracy to be based 14. _____ to the reproductive rates of other
(C) democracy be based small mammals, that of the bat is very low
(D) whenever democracy is based indeed.
(A) Compared
11. World trade patterns are indicative of the (B) It is compared
important economic issues _____ confront the (C) To be comparing
world today. (D) Have compared
(A) what 15. _____ native to Europe, the daisy has now
(B) that spread throughout most of North America.
(C) who (A) Although
(D) they (B) If it were
(C) In spite of
12. In the symphony orchestra, bass drums are (D) That it is.
not ___ kettle drums.
16. On Ellesmere Island in the Arctic one fossil forest consists of a nearly hundred large stumps
scattered on an exposed coal bed.
17. The surface conditions on the planet Mars are the more like the Earth’s than are those of any
other planet in the solar system.
18. The midnight sun is a phenomenon in which the Sun visible remains in the sky for twenty-four
hours or longer.
19. The Humber River and its valley form a major salmon-fishing, lumbering, hunting, and farmer
region in western Newfoundland, Canada.
20. Among the parameters that determine whether an environment is suitably for life as we know it
are temperature, water availability, and oxygen content.
21. When eggs of some species of insects hatch, the newly born insects look almost like its adult
counterparts.
22. Although there are more than 2,000 different variety of candy, many of them are made from a
basic boiled mixture of sugar, water, and corn syrup.
23. The capital of the United States, originally New York City, was moved to Philadelphia where
stayed until 1800.
24. Migration of animals may be initiated by physiological stimuli such as reproductive changes,
external pressures such as weather changes, or a combination of either types of changes.
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