1.    Iron production was revolutionized in the early eighteenth century when coke was first used instead of charcoal for refining iron ore.

2. Apart from its low cost, the appeal of iron as a building material lay in its strength, its resistance to fire, and its potential to span vast areas.

3. The use of exposed iron occurred mainly in the new building types spawned by the Industrial Revolution: in factories, warehouses, commercial offices, exhibition hall, and railroad stations

4. Designers of the railroad stations of the new age explored the potential of iron, covering huge areas with spans that surpassed the great vaults of medieval churches and cathedrals

5. The computer computes the positions and colors for the figures in the picture, and sends this information to the recorder, which captures it on film

6. Sometimes, however, the images are stored on a large magnetic disk before being sent to the recorder. Once this process is completed, it is repeated for the next frame.

8. Computer-animation companies first do motion tests with simple computer-generated line drawings before selling their computers to the task of calculating the high-resolution, realistic-looking images.

8. Yellow dyes, whether from weld or some other plant sources such as saffron or turmeric, invariably fade or disappear.

9. The range of natural colors was hugely expanded and, indeed, superseded by the chemical dyes developed during the eighteen hundreds

10. The strikingly new forms of architecture that appeared in the late nineteenth and twentieth
centuries were built to meet the needs of industry and of commerce 

11. About the middle of the nineteenth century, mechanized industrial production began to demand large, well-lighted interiors in which manufacturing could be carried on.

12. The marketing of industrial products necessitated large-scale storage spaces, and enormous shops selling under one roof a wide variety of items.

13. Hence, the characteristic new architectural forms of the late nineteenth and twentieth centuries have been the factory,

14. Stones suitable for use as anvils are not easy to find, and often a chimpanzee may carry a haul of nuts more than 40 meters to find a suitable anvil.

15.To make a twig more effective for digging out termites, for example, a chimp may first strip it of its leaves.

17.Surprisingly, there is also a species of bird that uses sticks to probe holes in the search for insects.

17. A print may exist in several versions.

18.. It is customary to number prints as they come off the press, the earlier impressions being the finest and therefore the most desirable.

19.Prints incorporate the same compositional principles, as paintings. Line, shape, or texture may be the predominant element according to the printing technique used

20. Printmaking is the generic term for a number of processes, of which woodcut and engraving are two prime
examples.

21.The artist inks the plate and wipes it clean so that some ink remains in the incised grooves.

22.Both woodcut and engraving have distinctive characteristics. Engraving lends itself to subtle modeling and
shading through the use of fine lines.

24. A set of multiples is called an edition. Both methods can yield several hundred good-quality prints before the original block or plate begins to show signs of wear.

24. Coded to refer to speech, the potential for communication through these dots and dashes—short and long intervals as the circuit is broken—is very great. 

26.The basic function of any signal is to impinge upon the environment in such a way that it attracts attention

27.Symbols are more difficult to describe than either signals or signs because of their intricate relationship with the receiver’s culture perceptions.

28. If done in unison, applauding can be a symbol of the audience’s discontent with the performance.

29.What forms of life were able to make such a drastic change in lifestyle?

30.It turns out that some fossils can be extracted from these sediments by putting the rocks in an acid bath.

31.In many instances the specimens are less than one-tenth of a millimeter in diameter.

32. Although they were entombed in the rocks for hundreds of millions of years, many of the fossils consist of the organic remains of
the organism.

33.The pressure exerted on the human body increases by 1 atmosphere for every 10 meters of depth in seawater, so that at 30 meters in seawater a diver is exposed to a pressure of about 4 atmospheres.

34.Deep dives are less dangerous if helium is substituted for nitrogen, because under these pressures helium does not exert a similar narcotic effect.

35. As a scuba diver descends, the pressure of nitrogen in the lungs increases. Nitrogen then diffuses from the
lungs to the blood and from the blood to body tissues.

36.The elliptical galaxies have a symmetrical elliptical or spheroidal shape with no obvious structure.

37. The light from the nearby Virgo galaxy set out when reptiles still dominated the animal world.

38. This change in volume may cause the lungs to distend and even rupture. This condition is called air embolism.