English Recordings

36.
The RPC, founded in 1996, describes itself as a progressive organization fighting for social change. It is a
multiracial, multi-issue, international membership organization.
Its mission is to move the nation and the world towards social, racial, and economic justice. It has its headquarters in Chicago, and major branches in Washington, D.C.,
New York, and Los Angeles. It has succeeded in registering hundreds of thousands of voters, helped elect many officials, mediated labor disputes, affected public policy
in Haiti, and helped secure professional positions for
minorities in a number of different fields. It also works on issues such as fair housing, gender equality, and
environmental justice.

37.
A water plant called the sacred lotus regulates its temperature in order to benefit insects that it needs to reproduce. When the plant flowers, it heats its blossoms to above 86ºF for as long as four days. It does so, even when the air is as cool as 50ºF . The heat releases an
aroma that attracts certain insects, which fly into the flower to feed on nectar and pollen. But according to
Roger Seymour and Paul Schultze-Motel of Australia’s University of Adelaide, the heat does more: It rewards insects with a stable environment that enhances their
ability to eat, mate, and prepare for flight.

38.
Old Hawk gestured up at the tall, old cottonwood. It was so large that a grown man could not put his arms
around it. “This tree,” he said, “has stood guard over our
family all its life. Strength is what I feel each time I look at it. Yet, there have been moments when its great strength was also its weakness.” “That’s hard to believe,”
Jeremy said. “It’s the biggest tree for miles around.” Old Hawk pointed at the chokecherry trees in a dry river bed not far away. “Look there,” he said, “those chokecherry
trees are small and weak in comparison to this cottonwood.
But when you were a child, they survived a storm without losing a branch. This old cottonwood, on the
other hand, lost several branches. It stood up to the storm, but it could not bend with the wind the way the chokecherry trees could.”

33.
Knowing when something happened is important.
Understanding why historic events took place is also important. To do this, historians often turn to geography.
Weather patterns, the water supply, and the landscape of a place all affect the lives of the people who live there. For example, to explain why the ancient Egyptians developed
a successful civilization, you must look at the geography of Egypt. Egyptian civilization was built on the banks of the Nile River, which flooded each year, depositing soil
on its banks. The rich soil could help farmers grow enough crops to feed the people in the cities. That meant everyone did not have to farm, so some people could perform other jobs that helped develop the civilization.

34.
Nowadays, we can enjoy athletic competition of every kind without leaving our homes. It is the fun that comes from cheering on our team and celebrating its skills while complaining about the opposing team’s good luck.
But some individuals sit and watch a football game or tennis match without cheering for anyone or any team.
They are not willing to risk the possible disappointment of picking the loser, so they give up the possible joy of picking the winner. They live in the world of neutrality.
Don’t be one of them. Sure, your team might lose. But then again, your team might win. Either way, your
spectator experience will have been a fun one, and you will have avoided being merely a passive observer.

35.
The above graph shows changes in school enrollment rates of the population ages 3-19 by age group from 1970 to 2006. The enrollment rates of all age groups were higher than 50 percent in 2006. Of all age
groups, the enrollment rate for youth ages 7-13 was the highest during the entire period covered by the graph.
Of all age groups, the enrollment rate of children ages 5-6 increased the most from 1970 to 2006. The
overall change in the enrollment rate from 1980 to 1990 was smaller for youth ages 14-17 than for youth ages 18-19. The lowest enrollment rate is seen in children ages 3-4 among all age groups for each year.

30.
Her nerves were hurting her. She looked automatically again at the high, uncurtained windows. As night fell, she could just perceive outside a huge tree swinging its
branches. The rain came flying on the window. Ah, why didn’t she have peace? These two men, her husband and
her son, why did they not come? She wrapped a large scarf around her and hesitated for a moment. She opened
the door and stepped out into the backyard. There was no sign of a light anywhere. She listened with all her ears but could hear nothing but the night. “James! Shawn!”
she called, but nothing came from the darkness.

31.
Sheets of paper exist almost entirely for the purpose of
carrying information, so we tend to think of them as neutral objects. We rarely interpret marks on paper as
references to the paper itself. However , when we see the text, characters, and images on artifacts that serve other purposes, we generally interpret these marks as labels that do refer to their carriers. Natural objects do not come with labels, of course, but these days, most physical artifacts
do. That is , their designers have chosen to shift part of the burden of communication from the form and materials of the artifact itself to lightweight surface symbols. So, for
example, a designer of door handles might not worry about communicating their functions through their shapes, but might simply mark them ‘push’ and ‘pull.’

32.
Many people believe that they will be free of their anger if they express it, and that their tears will release their pain. This belief derives from a nineteenth-century
understanding of emotions, and it is no truer than the flat earth. It sees the brain as a steam kettle in which negative feelings build up pressure. But no psychologist has ever succeeded in proving the unburdening effects of the
supposed safety valves of tears and anger. On the contrary, over forty years ago, controlled studies showed that fits of anger are more likely to intensify anger, and that tears can drive us still deeper into depression. Our heads do not
resemble steam kettles, and our brains involve a much more complicated system than can be accounted for by images taken from nineteenth-century technology.

CUBIC BORON NITRIDE (CBN)

Next to diamond, cubic boron nitride (CBN) is the hardest material presently available. Introduced in 1962, it is also used as an abrasive. Cubic boron nitride is made by bonding a 0.5 - 1 mm layer of polycrystalline cubic boron nitride to a carbide substrate by sintering under pressure. While the carbide provides shock resistance, the CBN layer provides very high wear resistance and cutting-edge strength. Cubic boron nitride tools are also made in small sizes without a substrate.
At elevated temperatures, CBN is chemically inert to iron and nickel, and its resistance to oxidation is high. It is, therefore, particularly suitable for cutting hardened ferrous and high-temperature alloys.
Because CBN tools are brittle, stiffness of the machine tool and fixturing is important in order to avoid vibration and chatter. Furthermore, in order to avoid cracking due to thermal shock, machining should generally be performed dry - i.e., cutting fluids should be avoided, particularly in interrupted cutting operations such as milling.

SILICON-NITRIDE BASED CERAMICS

Developed in the 1970s, silicon-nitride (SiN) based ceramic tool materials consist of silicon nitride with various additions of aluminium oxide, yttrium oxide and titanium carbide. These tools have toughness, hot hardness, and good thermal-shock resistance.
An example of a SiN-base material is sialon, named after the elements of which it is composed: silicon, aluminium, oxygen, and nitrogen. It has higher thermal-shock resistance than silicon nitride, and is recommended for machining cast irons and nickel-based super-alloys at intermediate cutting speeds. Because of chemical affinity to iron, SiN-based tools are not suitable for machining steels.

ALUMINA-BASED CERAMICS

Ceramic tool materials, introduced in the early 1950s, consist primarily of fine-grained, high-purity aluminium oxide. They are cold-pressed into insert shapes under high pressure and sintered at high temperature; the end product is referred to as white, or cold-pressed, ceramics. Additions of titanium carbide and zirconium oxide help improve properties such as toughness and thermal-shock resistance.
Alumina-based ceramic tools have very high abrasion resistance and hot hardness. Chemically, they are more stable than high-speed steels and carbides, so they have less tendency to adhere to metals during cutting and a correspondingly lower tendency to form a built-up edge. Consequently, in cutting cast irons and steels, good surface finish is obtained with ceramic tools. However, ceramics lack toughness, and their use may result in premature tool failure by chipping or catastrophic failure.
Ceramic inserts are available in shapes similar to the shapes of carbide inserts. They are effective in high-speed, uninterrupted cutting operations, such as finishing or semifinishing by turning. To reduce thermal shock, cutting should be performed either dry or with a copious amount of cutting fluid, applied in a steady stream. Improper or intermittent applications of the fluid can cause thermal shock and fracture of the ceramic tool.
Ceramic tool shape and setup are important. Negative rake angles (large included angles) are generally preferred in order to avoid chipping due to the poor tensile strength of ceramics. Tool failure can be reduced by increasing the stiffness and damping capacity of machine tools, mountings, and workholding devices, thus reducing vibration and chatter.

Cermets. Black, or hot-pressed, ceramics were introduced in the 1960s. They typically contain 70% aluminium oxide and 30% titanium carbide, and are also called "cermets" (from ceramic and metal). Other cermets contain molybdenum carbide, niobium carbide, and tantalum carbide. Although they have chemical stability and resistance to built-up edge formation, their brittleness and high cost have been a problem.
Further refinements of these tools have resulted in improved strength, toughness, and reliability. Their performance is somewhere between that of ceramics and carbides and has been particularly suitable for light roughing cuts and high-speed finishing cuts. Chip-breaker features are important for cermet inserts. Although cermets can be coated, the benefits of coatings are somewhat controversial; the improvement in wear resistance appears to be marginal.

Cutting tool material - Diamond

Of all known materials, the hardest substance is diamond. It has low friction, high wear resistance, and the ability to maintain a sharp cutting edge. Diamond is used when good surface finish and dimensional accuracy are required, particularly with soft nonferrous alloys and abrasive nonmetallic materials. Single-crystal diamond of various carats is used for special applications, such as machining copper-front precision optical mirrors for the Strategic Defense Initiative program.
Because diamond is brittle, tool shape and sharpness are important. Low rake angles (large included angles) are generally used to provide a strong cutting edge. Special attention should be given to proper mounting and crystal orientation in order to obtain optimum tool life. Wear may occur through microchipping (caused by thermal stresses and oxidation) and through transformation to carbon (caused by the heat generated during cutting).
Single-crystal diamond tools have been largely replaced by polycrystalline-diamond (PCD) tools, which are also used as wire-drawing dies for fine wire. These materials consist of very small synthetic crystals, fused by a high-pressure, high-temperature process to a thickness of about 0.5 to 1 mm and bonded to a carbide substrate; the result is similar to CBN tools. The random orientation of the diamond crystals prevents the propagation of cracks through the structure, significantly improving its toughness.
Diamond tools can be used satisfactorily at almost any speed, but are most suitable for light, uninterrupted finishing cuts. In order to minimize tool fracture, the single-crystal diamond must be resharpened as soon as it becomes dull. Because of its strong chemical affinity, diamond is not recommended for machining plain-carbon steels or titanium, nickel, and cobalt-based alloys. Diamond is also used as an abrasive in grinding and polishing operations and as coatings.

27.
When faced with things that are too big to sense, we comprehend them by adding knowledge to the experience.
The first appearance of a shining star in a darkening evening sky can take you out into the universe if you
combine what you see with the twin facts that the star is merely one of the closest of the galaxy’s 200 billion stars and that its light began traveling decades ago. The smell of gasoline going into a car’s tank during a refueling stop, when combined with the fact that each day nearly a billion gallons of crude oil are refined and used in the United States, can allow our imagination to spread outward into the vast global network of energy trade and politics.

28.
The first experiments in television broadcasting began
in France in the 1930s, but the French were slow to
employ the new technology. There were several reasons
for this hesitancy. Radio absorbed the majority of state resources, and the French government was reluctant to shoulder the financial burden of developing national networks for television broadcasting. Television
programming costs were too high, and program output correspondingly low. Poor distribution combined with minimal offerings provided little incentive to purchase the new product. Further, television sets were priced beyond the means of a general public whose modest living standards, especially in the 1930s and 1940s, did not allow the acquisition of luxury goods.
Ideological influences also factored in; elites in particular were skeptical of television, perceiving
it as a messenger of mass culture and Americanization.

29.
A violin creates tension in its strings and gives each of them an equilibrium shape: a straight line. A tight violin string can be viewed as composed of many individual pieces that are connected in a chain as in the above two figures. When the string is straight, as in
Figure 1, its tension is uniform, and the two outward forces on a given piece sum to zero; they have equal magnitudes and point in opposite directions. With no net forces acting on its pieces, the string is in equilibrium.
But when the string is curved, as in Figure 2, the outward forces on its pieces no longer sum to zero.
Although the string’s uniform tension still gives those outward forces equal magnitudes, they now point in slightly different directions, and each piece experiences a zero net force. The net forces on its pieces are
restoring forces, which will cause the string to vibrate and thus make sounds.

24.
While the fine art object is valued because it is unique, it is also valued because it can be reproduced
for popular consumption. For example, Van Gogh’s paintings
have been reproduced endlessly on posters, postcards, coffee mugs, and T-shirts. Ordinary consumers can own a copy of the highly valued originals. Therefore, the value of
the original results not only from its uniqueness but from its being the source from which reproductions are made.
The manufacturers who produce art reproductions and the consumers who purchase and display them give value to the work of art by making it available to many people as an item of popular culture.

25.
There are some people who believe that no one should be trusted. They usually feel this way because their
behavior compels others to lie to them. In other words, they make it difficult for others to tell them the truth because they respond rudely or emotionally to people who
tell the truth. If others see how angry, hurt, or hateful you become when they tell you the truth, they will avoid telling it to you at all costs. If you are known as someone who is easily offended, you will never know what others are really
thinking or feeling because they will distort the truth to escape from your negative reaction. If you demand that children tell you the truth and then punish them because it
is not very satisfying, you teach them to lie to you to protect themselves.

26.
One of the main principles I follow when I draw outside is not to select a subject that is too difficult or odd. I try to stay away from houses or barns that have unusual angles of the roof, or objects that look incorrect in size, perspective, or design.
If the subject is confusing when you look at it, it will be more confusing when you attempt to draw it. I know a beautiful barn where the corners are not at right angles. No matter how many times I have drawn it, the perspective does
not look right. If I were to make an accurate drawing of this barn and put it in a show, I’m sure I would get all kinds of criticism for my poor perspective. I would not be there to tell my critics that the barn is actually constructed this way.
So, I stay away from subjects that do not look right to me.

21.
Many social scientists have believed for some time that birth order directly affects both personality
and achievement in adult life. In fact, people have been
using birth order to account for personality factors such
as an aggressive behavior or a passive temperament. One
might say, “Oh, I’m the eldest of three sisters, so I can’t
help that I’m so overbearing,” or “I’m not very successful
in business, because I’m the youngest child and thus less aggressive than my older brothers and
sisters.” Recent studies, however, have proved this belief to be false. In other words, birth order may define your role within a family, but as you mature into adulthood, accepting other social roles, birth order becomes insignificant.

22.
You may think that moving a short distance is so easy that you can do it in no time with little effort. You may decide to use your own car because you think that you don’t need the services of a moving company. Well, you might be wrong. You are under the false impression that you do not have as many items to pack as you really do.
You find out too late that your car cannot carry as much as you thought it could. So, it takes you far more
trips to your new home than you thought it would. There is also the possibility of damaging your stuff, some of it valuable. All these things considered, it might be better
to ask for the services of a moving company.

23.
Roman doll-makers continued to use technology developed by the Egyptians and Greeks, but in line with the artistic sensibilities of their culture, they were constantly trying to make dolls more elegant and
beautiful. One doll, found near Prati in Rome, was made of ivory and lay beside her owner who had died at the age of eighteen. The huge growth in the understanding of civilization raised awareness of other important roles of trade. Next to the doll was a small box, also made of ivory, containing tiny combs and a silver mirror.
The doll had rings on her fingers and held a tiny key,
which unlocked the box. Like children today, the
younger members of Roman civilization would have
dressed and undressed their dolls, and decorated their hair
and fingers according to the latest fashions.