Active Voice
Present Participle
Throwing --- , , ,
The boy throwing stones into the pond is my brother.
, , .
The boy throwing stones into the pond laughed loudly.
, , .
The boy stood on the bank throwing stones into the pond.
, .
Throwing the letter into the fire he left the room.
, .
Perfect Participle
Having thrown
Having thrown the ball into the water, the boy could not get it back.
, .
Passive Voice
Present Participle
Being thrown , , ()
The stones being thrown by the boys are galling into the water.
, , .
Being thrown with great force, the stone reached the opposite bank. ( ) , .
Past Participle
Thrown ,
Stones thrown into the water go to the bottom.
, , .
The stone thrown by the boy reached the bank/
, , .
Perfect Participle
Having been thrown ( )
Having once been thrown into the water by the children, the dog always ran away when it saw them.
, .
Exercise.
a) Participle I
1. A molecule is a compound consisting of two or more atoms.
2. Combining hydrogen with oxygen in the proportion of two atoms of hydrogen and one atom of oxygen we produce water.
3. While burning different substances combine with oxygen.
4. The assistant was preparing the solution very carefully.
5. The solution is boiling.
6. The boiling solution has neither color nor odour.
b) Participle II
1. The solution of the problem required concentrated efforts of many scientists.
2. The data required were analyzed in our laboratory.
3. When required, the data will be applied in our practical work.
4. The investigations analyzed resulted in an interesting discovery.
5. Heated glass is plastic.
6. When heated, glass can be easily worked.
7. Some new properties of the polymer found during the experiments were quite unexpected.
Optical technology
.
Fiber, improve, reliability, noteworthy, ultra-thin, technique, transparency, waveguide, storage, indestructible, versatile
Words to be learnt
optical fiber
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to replace ,
to promise
capacity ,
reliability
set in motion
a train of events
long-lived source
low loss
technique
incredible
transparency
coherent form
waveguide
to accommodate ,
storage , ,
underway , ,
indestructible
thin film
versatile
noteworthy ,
Text
One of the most interesting developments in telecommunication is the rapid progress of optical communication where optical fibers are replacing conventional telephone wires and cables. Just as digital technologies greatly improved the telephone system, optical communication promises a considerable increase in capacity, quality, performance and reliability of the global telecommunication network. New technologies such as optical fibers will increase the speed of telecommunication and provide new, specialized information service. Voice, computer data, even video images, will be increasingly integrated into a single
digital communication network capable to process and transmit virtually any kind of information.
The advent of the laser in the early 1960 set in motion a train of events that is steadily changing the outlook for optical communication. The past few years have been made three important advances. One was the invention of the semiconductor-diode laser, which satisfied the need for a cheap, efficient and long-lived source of coherent light waves to serve as the carrier waves for encoded signals. Another noteworthy advance was the development of ultra-thin, low-loss optical fibers, which are well suited for the long-range transmission of light waves, and, finally, an entire new generation of compact optical devices based on the precise guiding of laser light is being devised. Two technologies were combined: the laser, first demonstrated in 1960, and the fabrication 10 years later of ultra-thin silicon fibers which can serve as light wave conductors. With the further development of very efficient lasers plus continually improved techniques to produce thin silica fibers of incredible transparency, optical systems can transmit pulses of light as far as 135 kilometers without the need for amplification or regeneration.
At present high-capacity optical transmission systems are being installed between many major cities at a rapid rate. This system has a number of basic constituents. First, there must be an oscillator of some kind to generate the carrier waves in a highly coherent form (that is, with the all in step at the same frequency). Next, the waves must be modulated to carry information by varying either their frequency or their amplitude. The modulated microwave beam is then transmitted either by channeling it through a metallic waveguide or by propagating it through the atmosphere. The system most widely used now operates at 147 megabits (thousand bits) per second and accommodates 6 000 circuits over a single pair of glass fibers (one for each direction of transmission). This system will soon be improved to operate at 1.7 gigabits (thousand million bits) per second and handle 24 000 telephone channels simultaneously.
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A revolution in information storage is underway with optical disk technology. The first optical disks appeared in the early 1970-s. They were and are used to record video films, but in a continuous spiral rather than digitally. The first digital optical disks were produced in 1982 as compact disks for music. They were further developed as a storage medium for computers. The disks are made of plastics coated with aluminium. The information is recorded by using a powerful laser to imprint bubbles on the surface of the disk. A less powerful laser reads back
the pictures, sound or information. An optical disk is almost indestructible and can store about 1 000 times more information than a plastic disk of the same siz.
The latest optical disk development is a system which enables computer users to record their own information on a glass or plastic disk coated with a thin film of tellurium. Such a disk can store 200 megabytes (200 million characters).Besides, it is reported that an optical equivalent of a transistor has been produced and intensive research on optical electronic computers is under way at a number of US companies as well as in countries around the world. It is found that optical technology is cost-effective and versatile. It finds new application every day from connecting communication equipment or computers within the same building or room to long distance transcontinental, transoceanic and space communications.
I. . .
1. a) Optical communication provides a new generation of communication satellites
b) Optical communication promises a considerable increase in networks
c) Optical communication promises a considerable increase in capacity, quality, performance and reliability of the global telecommunication networks
2. a) One advance was the invention of the coherent light waves
b) One advance was the development of a new type of diodes
c) One advance was the invention of the semiconductor-diode laser
3. a) Optical systems can transmit ultra-high frequencies
b) Optical systems can transmit pulses of light without the need for amplification or regeneration
c) Optical systems cant transmit pulses of light without the need for regeneration
4. a) There must be an semiconductor of some kind to generate the carrier waves in a highly coherent form
b) There must be modulated waves to carry information by varying either their frequency or their amplitude
c) There must be oscillator to transmit microwave beam
5. a) The modulated microwave beam is transmitted by the optical disks
b) The modulated microwave beam is transmitted by propagating it through the atmosphere
c) The modulated microwave beam is transmitted either by channeling it through metallic waveguide or by propagating it through the atmosphere
6. a) The first optical disks appeared in the early 1970-s
b) The first optical waveguide appeared in the early 1970-s
c) The first optical system appeared in the early 1970-s
7. a) The lasers were developed as a storage medium for computers
b) The first digital optical disks were developed as a storage medium for waveguide
c) The first digital optical disks were developed as a storage medium for computers
8. a) The optical technology is inefficient
b) The optical technology is one-sided
c) The optical technology is cost-effective and versatile
II. . . .
III. , Optical technology.
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Unit 19.
Grammar Revision
