题目内容
The rejection of the Impressionist exhibition by critlies was caused by which of the following？
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According to the passage, the white color of the smoke particles generated by a flashbulb
In the early decades of the United States. the agrarian movement promoted the farmer
as society's hero. In the minds of agrarian thinkers and writers. the farmer was a person on whose
well-being the health of the new country depended. The period between the
Revolution, which ended in 1783,and the Civil War. which ended in 1865.was the age of
(5) the farmer in the United States. Agrarian philosophers. represented most eloquently by
Thomas Jefferson, celebrated farmers extravagantly for their supposed centrality in a good
society, their political virtue. and their Superior morality. And visually all policy makers, whether
they subscribed to the tenets of the philosophy held by Jefferson or not, recognized agriculture as
the key component of the American economy. Consequently, government at
(10)all levels worked to encourage farmers as a social group and agriculture as economic
enterprise.
Both the national and state governments developed transportation infrastructure, building
canals, roads, bridges, and railroads, deepening harbors, and removing obstructions from navigable
streams. The national government imported plant and animal varieties and
(15)launched exploring expeditions into prospective farmlands in the West. In addition,
government trade policies facilitated the exporting of agricultural products.
For their part. farmers seemed to meet the social expectations agrarian philosophers
had for them. as their broader horizons and greater self-respect, both products of the
Revolution were reflected to some degree in their behavior. Farmers seemed to become
(20)more scientific.joining agricultural societies and reading the farm newspapers that sprang
up throughout the country. They began using improved implements, tried new crops and
pure animal breeds, and became more receptive to modern theories of soil improvement.
They also responded to inducements by national and state governments. Farmers
streamed to the West. filling frontier lands with stunning rapidity. But farmers responded
(25)less to the expectations of agrarians and government inducements than to growing market
opportunities. European demand for food from the United States seemed insatiable. War,
industrialization, and urbanization all kept demand high in Europe. United States cities
and industries grew as well; even industries not directly related to farming thrived because
of the market, money. and labor that agriculture provided.
What does the passage mainly discuss？
A．His houses were often smallB．His designs were overly simpleC．His roofs often leakedD
Most sources of illumination generate light over an appreciable period, and indeed if
an object is lit for a very brief time(less that 1/25 second), the human eye will not react
in time to see the object. A photographic emulsion---that is, a light-sensitive coating on
photographic film, paper, or glass--will, however, record much shorter bursts of light. A
(5) photographic flash can therefore be used to capture high-speed movement on film as well
as to correct deficiencies of the normal surrounding lighting. Photoflash is now generated
electronically, but the earliest form, first used in 1864, was a paper bag containing
magnesium wire and some oxygen-rich substance, such as potassium chlorate. When the
bag was ignited, the metal burned with an intense flash. A contemporary observer reported
(10) that "this quite unsafe device seems to have done nothing worse that engulf the room in
dense smoke and lead to pictures of dubious quality and odd poses."
The evolution of the photoflash was slow, flashbulbs, containing fine wire made of a
metal, such as magnesium or aluminum, capable of being ignited in an atmosphere of pure oxygen
at low pressure, were introduced only in the 1920's.In the earliest type, the metal
(15) was separated from the oxygen by a thin glass bulb. The dash was fired by piercing the
bulb and allowing the oxygen to come into contact with the metal, which ignited
spontaneously. Later bulbs were fired by an electric battery, which heated the wire by
passing a small current through it. Other combinations, such as the pairing of oxygen
difluoride with zirconium, have also been used. In each case enough energy is given out to
(20) heat the oxidizable metal momentarily to a white-hot emission of visible light. The smoke
particles are so small that they cool rapidly; but since they are white, they contribute to the
brilliance by reflecting the light from their still-glowing neighbors. A slightly bigger form
of the metal will burn for a longer time.
What does the passage mainly discuss？
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