61.The argument that humans，even in prehistoric times，had some number sense，at least to the extent of recognizing the concepts of more and less when some objects were added to or taken away from a small group，seems fair．for studies have shown that some animals possess such a sense．
62.A useful definition of an air pollutant is a compound added directly or indirectly by humans to the atmosphere in such quantities as to affect humans, animals，vegetation，or materials adversely．
63．The acute，growing public awareness of the social changes that had been taking place for some time was tied to tremendous growth in popular journalism in the late nineteenth century，including growth in quantity and circulation of both magazines and newspapers．
64．A detailed study has been made of the prints using photogrammetry，a technique for obtaining measurements through photographs，which created a drawing showing all the curves and contours of the prints．
65．Footprints thus provide US not merely with rare impressions of the soft tissue of early hominids，but also with evidence of upright walking that in many ways is clearer than can be obtained from the analysis of bones．
66．In fact，throughout the animal kingdom，from sponges to certain types of worms，shellfish，and all vertebrates(creatures possessing a spinal column), there is evidence that transplants of cells or fragments of tissues into an animal are
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accepted only if they come from genetically compatible or closely related individuals．
67．In the twenties，jazz became the hottest new thing in dance music, much as ragtime had at the turn of the century，and as would rhythm and blues in the forties，rock in the fifties，and disco in the seventies．
68．They made these quilt until the advent of the Revolutionary War in 1775，when everything English came to be frowned upon．
69．Growing tightly packed together and collectively weaving a dense canopy of branches, a stand of red alder trees can totally dominate a site to the exclusion of almost everything else.
70．In taking up a new life across the Atlantic，the early European settlers of the United States did not abandon the diversions with which their ancestors had traditionally relieved the tedium of life．
71． Farm dwellers in their isolation not only found it harder to locate companions in play but also thanks to the unending demands and pressures of their work, felt it necessary to combine fun with purpose.
72．The scientific investigation of an experience as private as consciousness is frustratingly beyond the usual tools of the experimental psychologist.
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73．Among the species of seabirds that use the windswept cliffs of the Atlantic coast of Canada in the summer to mate，lay eggs，and rear their young are common murres, Atlantic puffins，black-legged kittiwakes，and northern gannets．
74．The advantage of nesting on cliffs is the immunity it gives from foxes, which cannot scale the sheer rocks，and from ravens and other species of gulls, which have difficulty in landing on narrow ledges to steal eggs.
75．Their distrust was caused，in part，by a national ideology that proclaimed farming the greatest occupation and rural living superior to urban living·
76．A few art collectors Tames Bowdoin III of Boston，William Byrd of Virginia，and the Aliens and Hamiltons of Philadelphia introduced European art traditions to those colonists privileged to visit their galleries，especially aspiring artists．and established in their respective communities the idea of the value of art and the need for institutions devoted to its encouragement．
77．The achievements of the colonial artists，particularly those of Copley，West, and Peale，lent credence to the boast that the new nation was capable of encouraging genius and that political liberty was congenial to the development of taste——a necessary step before art could assume an important role in the new republic．
78．The railroad simultaneously stripped the landscape of the natural resources，made velocity of transport and economy of scale necessary parts of
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industrial production，and carried consumer goods to households.
79．Moreover，in addition to its being a transportation pathway equipped with a mammoth physical plant of tracks signals，crossings，bridges，and junctions，plus telegraph and telephone lines, the railroad nurtured factory complexes，coat piles, warehouses，and generating stations，forming along its right of way what has aptly been called “the metropolitan corridor” of the American landscape.
80.The Native Americans of northern California were highly skilled at basketry，using the reeds，grasses，barks，and roots they found around them to fashion articles of all sorts and sizes—not only trays，containers，and cooking pots，but hats，boats，fish traps，baby carriers，and ceremonial objects．
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