Reading Comprehension

1. Methodology & Mathematics
1.1. In science, a theory is a reasonable explanation of observed events that are related. A theory often involves an imaginary model that helps scientists picture the way an obseved event could be produced. A good example of this is found in the kinetic molecular theory, in which gases are pictured as being made up of many small particles that are in constant motion.

A useful theory, in ad***ion to explaining past observations, helps to predict events that have not as yet been observed. After a theory has been publicized, scientists design experiments to test the theory. If observations confirm the scientists'''' predictions, the theory is supported. If observations do not confirm the predictions, the scientists must search further. There may be a fault in the experiment, or the theory may have to be revised or rejected.

Science involves imagination and creative thinking as well as collecting information and performing experiments. Facts by themselves are not science. As the mathematician Jules Henri Poincare said: "Science is built with facts just as a house is built with bricks, But a collection of facts cannot be called science any more than a pile of bricks can be called a house. "

Most scientists start an investigation by finding out what other scientists have learned about a particular problem. After known facts have been gathered, the scientist comes to the part of the investigation that requires considerable imagination. Possible solutions to the problem are formulated. these possible solutions are called hypotheses.

In a way, any hypothesis is a leap into the unknown. It extents the scientist''''s thinking beyond the known facts. The scientist plans experiments, performs calculations and makes observations to test hypotheses. For without hypotheses, further investigation lacks purpose and direction. When hypotheses are confirmed, they are incorporated into theories.


1.2. It is said that mathematics is the base of all other sciences, and that arithmetic, the science of numbers, is the base of mathematics. Numbers consist of whole number (integers) which are formed by the digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 and by the combinations of them. For example, 247 õ?" two hundred and forty seven õ?" is a number formed by three digits. Parts of numbers smaller than 1 are sometimes expressed in terms of fractions, but in scientific usage they are given as decimals. This is because it is easier to perform the various mathematical operations if decimals are used instead of fractions. The main operations are: to add, subtract, multiply, and divide; to square, cube, or raise to any other power; to take a square, cube, or raise to any other roots, and to find a ratio or proportion between pairs of numbers or a series of numbers. Thus, the decimal, or ten-scale, system is used for scientific purposes throughout the world, even in countries whose national system of weights and measurements are based upon other scales. The other scale in general use nowadays in the binary, or two-scale, in which numbers are expressed by combinations of only two digits, 0 and 1. Thus, in the binary scale, 2 is expressed as 010, 3 is given as 011, 4 is represented as 100, etc. This scale is perfectly adapted to the õ?ooff-onõ? pulses of electricity, so it is widely used in electronic computers. Because of its simplicity it is often called õ?othe lazy schoolboyõ?Ts dream!õ?.


1.3. Marjorie Rice was an unlikely candidate for the role of mathematical innovator. She had no formal education in mathematics save a single course required for graduation from high school in 1939. Nonetheless, in 1975 she took up a problem that professional mathematicians had twice left for dead, and showed how much life as in it still.

The problem was tessellation, or tiling of the plane, involves taking a single closed figure a triangle, for example, or a rectangle and fitting it together with copies of itself so that a plane is covered without any gaps or overlap. A region of this plane would look rather like a jigsaw puzzle whose pieces are all identical. Rice worked primarily with polygons, which consist only of straight lines. More specifically, she worked with convex polygons, in which the line joining any two points on the polygon lies entirely within the polygon itself or on one of its edges (A five-pointed star, for example, does not qualify as a convex polygon. )

By the time Rice took up tiling, its basic properties had been established. Obviously, any square can tile the plane, as many kitchen floors have demonstrated. Equilateral triangles are also a fairly clear-cut case. There is one other regular polygon(a polygon whose angles, and sides, are equal) that can tile the plane: the hexagon. This fact was established by the ancient Greeks but had long before been exploited by honeybees in building their honeycombs.

And what of irregular polygons? As it turns out any triangle or quadrilateral, no matter how devoid of regularity, will tile the plane. On the other hand, no convex polygon with more than six sides can do so, and the three classes of convex hexagons that can were uncovered by the end of the First World War. So the only real question left by the time Marjorie Rice began her work was which convex pentagons tile the plane.

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2. Physics.

2.1. When a ray of light hits the surface of an object, one or a combination of the following three things happens: the light may be thrown back towards the source of the light (reflection), it may be passed through the object (refraction), or it may be absorbed into the object. Different materials and substances have unique patterns in the way light behaves when it falls upon them. This pattern gives objects their special appearance and color. If an object allows light to pass directly through it, as does a totally clear sheet of glass, it is said to be transparent. If it scatters and diffuses the light, in a manner similar to a frosted pane of glass, it is translucent. Finally, if it obstructs the passage of the light it is deem opaque.

When light is shined upon a reflecting object, it makes a certain angle with an imaginary line that is a right anglers, or õ?onormal,õ? with that object. This angle is called the angle of incidence. The ray that is reflected from the object also makes an angle with the normal line. This is termed the angle of reflection. The law of reflection dictates that the angle of incident is always equal to the angle of reflection. In a reflecting object with a smooth surface, like a mirror; the light reflects back without spreading out; however, if the object is rough, the light does spread out. This explains why light reflected from a mirror form such as a sharp image while that form a piece of cloth forms no image at all. The law of refection holds true in any case.

When light is refractedá it slows down as it passes through the substance. If it enters the object at an angle other than a right angle, this slowing down causes the light to bend at the surface of the substance. This accounts for the well-known example of a pencil appearing to bend if it is placed in a glass of water.

When a material absorbs light, the light either raised the energy level of the materialõ?Ts atoms, or the light may be converted into heat energy. The most common example of the latter is that objects left in sunshine tend to heat up form the absorption of life.


2.2. The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is hard to imagine what life would be like without them. When there is a power failure, people grope about in flickering candlelight, cars hesitate in the streets because there are no traffic lights to guide them, and food spoils in silent refrigerators.

Yet, people began to understand how electricity works only a little more than two centuries ago. Nature has apparently been experimenting in this field for millions of years. Scientists are discovering more and more that the living won may hold many interesting secrets of electricity that could benefit humanity.

All living cells send out tiny pulses of electricity. As the heart beats, it set out pulses of recorded, they form an electrocardiogram, which a doctor can study to determine how well the heart is working. The brain, too, sends out brain waves of electricity, which can be recorded in an electroenephalogram. The electric currents generated by most living cells are extremely smalloften so small that sensitive instruments are needed to record them. But in some animals, certain muscle cells have become so specialized as electrical generators that they do not work as muscle cells at all. When large numbers of these cells are linked together, the effects can be astonishing.

The electric eel is an amazing storage battery It send a jolt of as much as eight hundred volts of electricity through the water in which it lives (An electric house current is only one hundred twenty volts. ). As many as four-fifths of all the cells in the electric eel''''s body are specialized for generating electricity, and the strength of the shock it can deliver corresponds roughly to the length of its body.


2.3. The word laser was coined as an acronym for Light Amplification by the Stimulated Emission of Radiation. Ordinary light, from the Sun or a light bulb, is emitted spontaneously, when atoms or molecules get rid of excess energy by themselves, without any outside intervention. Stimulated emission is different because it occurs when an atom or molecule holding onto excess energy has been stimulated to emit it as light.

Albert Einstein was the first *****ggest the existence of stimulated emission in a paper published in 1917. How ever, for many years physicists thought that atoms and molecules always were much more likely to emit light spontaneously and that stimulated emission thus always would be much weaker. It was not until after the Second World War that physicists began trying to make stimulated emission dominate. They sought ways by which one atom or molecule could stimulate many others to emit light, amplifying it to much higher powers.

The first *****cceed was Charles H. Townes, then at Columbia University in New York. Instead of working with light, however, he worked with microwaves, which have a much longer wavelength, and built a device he called a õ?omaster,õ? for Microwave Amplification by the Stimulated Emission of Radiation. Although he thought of the key idea in 1951, the first master was not completed until a couple of years later. Before long, many other physicists were building masers and trying to discover how to produce stimulated emission at even shorter wavelengths.

The key concepts emerged about 1957. Townes and Arthur Schawlow, then at Bell Telephone Laboratories, wrote a long paper outlining the con***ions need to amplify stimulated emission of visible light waves. At about the same time, similar ideas crystallized in the mid of Gordon Gould, then a 37-year-old graduate student at Columbia, who wrote them down in a series of notebooks. Towners and Schawlow published their ideas in a scientific journal, Physical Review Letters, but Gould filed a patent application. Three decades later, people still argue about who deserves the cre*** for the concept of the laser.


2.4. The semiconductor laser changes electric signals to optical signals and is extensively used in the making Computer Discs (CDs) and fiber optic communications. The recording of computer data and music on a disc is done through a laser beam that makes small pits on the disc. Computer discs with gigantic storage space are referred to as CD-ROM (Compact Disc Read-Only Memory)

Semiconductors are the most frequently used lasers because of their small size, light weight, and limited demand for energy. The semiconductor in the laser is constructed of two different pieces of semiconductor material having unlike electric characteristics. After these two pieces are connected and stimulated by using electric current, the laser emits coherent light which moves in a parallel path, divergent from incoherent light.

Gas lasers are glass tubes filled by a gas or a combination of gases, for instance, neon, helium, carbon dioxide, and krypton. Through stimulating electrical current and using different gases, various light beams can be produced. Carbon dioxide, used as a medium, emits infrared light and it works in the 1 to 1 million watt range. Gas laser are desirable for welding and cutting metals. The low-powered lasers, no more than a few hundred watts, on the other hand, are widely used for cutting wood, fabric, ceramics, and plastic.

In recent years, the uses of the laser have constantly increased. Overall, lasers have several advantages over conventional methods of production. First, they are compact, therefore, they require little space. Second, they need not bee fastened to the work area since they do not jar while operating. Third, the heat energy produced is directed to the exact location they are working on, consequently, they do not warm up or possibly destroy the other parts of the object that is being worked on.

Laser beam programmable controls include information storage retrieval, laser surgery, holography, high-speed scanner, land laser printing.


2.5. In this era of increased global warming and diminishing fossil fuel supplies, we must begin to put a greater priority of harnessing alternative energy sources. Fortunately, there are a number of readily available, renewable resources that are both cost-effective and earth-friendly. Two such resources are solar power and geothermal power.

Solar energy, which reaches the earth through sunlight, is so abundant that it could meet the needs of worldwide energy consumption 6,000 times over. And solar energy is easily harnessed through the use of photovoltaic cells that convert sunlight into electricity. In the United States alone, more than 100,000 homes are equipped with solar electric systems in the form of solar panels or solar roof tiles. And in other parts of the world, including many developing countries, the use of solar systems is growing steadily.

Another alternative energy source, which is abundant in specific geographical areas, is geothermal power, which creates energy by tapping heat from below the surface of the earth. Hot water and steam that are trapped in underground pools are pumped to the surface and used to run a generator, which produces electricity. Geothermal energy is 50,000 times more abundant than the entire known supply of fossil fuel resources. And as with solar power, the technology needed to utilize geothermal energy is fairly simple. A prime example of effective geothermal use is in Iceland, a region of high geothermal activity, where over 80 percent of private homes are heated by geothermal power.

Solar and geothermal energy are just two of a number of promising renewable alternatives to conventional energy sources. The time is long overdue to invest in the development and use of alternative energy on a global scale.


2.7. Almon Strowger, an American engineer, constructed the first automatic telephone switching system, which had a horizontal, bladelike contact arms, in 1891. The first commercial switchboard based on his invention opened in La Porte, Indiana, a year later and was an instant success with business users. To access the system, the caller pressed buttons to reach the desired number and turned the handle to activate the telephone ringer. During the same year, Stowgerõ?Ts step-by-step call advancement technology was implemented in the long-distance service between New York and Chicago when it proved to have the capacity of carrying signals through cable-joint extensions.

The first actual dial telephones, patented by Lee De Forest in 1907, were installed in Milwaukee in 1896. In 1912, their sound transmittal apparatus adapted an electronic tube to function as an amplifier. Transatlantic radio-telephone service linked New York and London in 1927. However, the long distance coaxial cable, which was hailed as unprecedented, came on the scene in 1936 connecting New York and Philadelphia. The Bell Laboratories research facility came up with the transistor to replace the cumbersome vacuum tube, thus diminishing the size of the electronic switch system to about 10 percent of that of the original. Crossbar switching, installed in terminals in 1938, operated on the principle of an electromagnetic force, which rotated horizontal and vertical bars within a rectangular frame and brought contacts together in a split second. A technological breakthrough in the form of underseas cables between the United States and Hawaii was implemented almost twenty years later. An extension was connected to Japan in 1964.

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Well nguyenthanhchuong, it really takes quite a long time to read thoroughly your post and to digest it. I''m just wondering why the name of the topic is "Toefl reading comprehension". Well, anyone learning TOEFL can easily realize this is NOT the type of Reading Comprehension in a TOEFL test. In Toefl, we have 5 passages to read in 55 minutes and they''re not this long. This is more of an article on science than a passage taken from a TOEFL test. Anyway, thank you for your contribution. You''re doing a good job, man!
As we go on, we remember all the times we had together
As our lives change, come whatever
We will still be FRIENDS FOREVER

I am sorry but i have to say that your article is not related to the TOEFL Comprehention at all. Hey, are you trying to learn the typing skills?. I myself believe that most of us often get the highest score in the Reading Comprehention part because we often spend lots of our time reading many kinds of books written in English. That''s the problem of Vocabulary, right?

Always in the state of being a silly chicken. I love the way you are, my friends.

Cha`o mọi người, mình đang bị bế tắc ở bài đọc của IELTS, và mình biết sau này, muuốn hiểu biết thì cách đọc là cực kỳ quan trọng, làm sao trong một thời gian ngắn nhất, đọc được nhiều nhất và lĩnh hội được nhiều nhất, bạn nào có kinh nghiệm thì chỉ mình với, mình đang điên cái đầu đây nè! IELTS ơi là IELTS......

Mình cũng đang điên cái đầu đây nè. TOEFL ơi là TOEFL!!!
Bài đọc hiểu có 5 bài làm trong 55 phút. Chiến thuật phân bố thời gian cho bài đọc hiểu thế nào nhỉ mọi người.
Như vậy là mỗi bài đọc hiểu chúng ta có 11 phút nhỉ? Trước khi bắt đầu đọc 1 bài, mình sẽ để ra 30 giây để đọc 9 câu hỏi xem nó hỏi những gì (câu đầu đa số không cần đọc cũng biết nó hỏi cái gì). Như vậy, còn 10 phút 30 giây. Các bạn thường dành bao nhiêu thời gian để đọc bài đọc hiểu và bao nhiêu thời gian để trả lời câu hỏi?