55.　For　centuries　waterwheels　were　the　only　sources　of　power　aside　from　human　and　animal　strong.

56.　The　age　of　a　geological　sample　can　be　estimated　from　the　ratio　of　radioactive　to　nonradioactive　carbon　present　in　the　object　is　examined.

57.　Salmon　spend　most　of　their　adult　lives　in　salt　water,　despite　they　return　to　their　freshwater　birthplaces　to　spawn　and　die.

58.　Porcelain　is　not　a　single　clay,　and　a　compound　of　kaolin,　ball　clay,　feldspar,　and　silica.

59.　the　dromedary　camel　is　raised　especially　to　racing.

60.　The　texture　of　soil　is　determined　by　the　size　of　the　grains　or　particles　that　make　up.

61.　All　matter　resists　any　change　in　their　condition　of　rest　or　of　motion.

62.　Like　some　other　running　birds,　the　sanderling　lacks　a　back　toe　and　has　a　three-toed　feet.

63.　Large　bodies　of　water　and　the　prevalence　of　moisture-bearing　winds　often　produce　a　condition　of　tall　humidity,　affecting　the　local　weather.

64.　a　thorough　study　of　mythology　requires　familiarity　for　the　properties　of　plants　and　trees,　and　the　habits　of　wild　birds　and　beasts.

65.　Seismology　has　not　reached　yet　the　stage　where　earthquakes　can　be　foretold　with　a　great　deal　of　accuracy.　

66.　At　night　the　desert　floor　radiates　heat　back　into　the　atmosphere　and　temperature　may　be　drop　to　near　freezing.

67.　The　continental　divide　refers　to　an　imaginary　line　in　the　North　American　Rockies　that　divides　the　waters　flowing　into　the　Atlantic　Ocean　from　it　flowing　into　the　Pacific.

68.　In　every　society　there　are　norms　that　say　individuals　how　they　are　supposed　to　behave.

69.　Due　to　the　refraction　of　light　rays,　this　is　impossible　for　the　naked　eye　to　determine　the　exact　location　of　a　star　close　to　the　horizon.

70.　Birds’　eggs　vary　greatly　of　size,　shape,　and　color.

71.　One　of　the　most　difficult　questions　in　defining　sleep　is　“What　is　the　functions　of　sleep?”

72.　Seven　of　planets　rotate　in　the　same　direction　as　their　orbital　motions,　while　Venus　and　Uranus　rotate　in　the　opposite　direction.

73.　A　microphone　enables　a　soft　tone　to　be　amplified,　thus　making　it　possible　the　gentle　renditions　of　romantic　love　songs　in　a　large　hall.

74.　Atrophy　is　a　decrease　in　size　of　a　cell,　organ,　tissues,　or　other　part　of　the　body　such　as　a　limb.

75.　Physical　fitness　activities　can　lead　to　an　alarming　variety　of　injuries　if　participants　push　themselves　greatly　hard.

76.　The　structure　or　behavior　of　many　protozoa’s　are　amazingly　complex　for　single-celled　animals.　

77.　The　word　“shore”　can　be　used　rather　of　“coast”　to　mean　the　land　bordering　the　sea.

78.　A　fable　is　usually　a　short　tale　featuring　animals　or　inanimate　objects　that　can　talk　and　think　alike　humans.

79.　Since　flounders　have　markings　that　blend　with　their　surroundings,　it　can　lie　camouflaged　on　the　bottom　of　the　ocean.

80.　the　aging　process　is　not　entirely　determined　by　heredity,　but　is　influenced　by　different　environmental　and　social　circumstances　as　good.

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