Filleachofthenumberedblanksinthefollowingpassagewithonesuitableword.
Fromthebeginning, waterhasfurnishedmanwithasourceoffoodandahighwaytotravelupon. Thefirstcivilisationsarose____________ (1) waterwasadominantelementintheenvironment, achallenge__________(2) mansingenuity. TheEgyptiansinventedthe 365___________ (3) calendarinresponse___________ (4) theNilesannualflooding. TheBabylonians, whowereamong ___________ (5) mostfamouslaw-makers___________ (6) antiquity, devisededictsregulatingwaterusage. WaterinspiredtheChinese___________ (7) builda 1,000 milecanal, acomplexsystem___________ (8), afternearly 2,500 years, ___________ (9) stillpartlyinuseandstillcommandstheaweofengineers. Buttheancientsneverfoundcompletesolutions ____________ (10) theirwaterproblems. TheHwangHo, orYellowRiver, isalsoknown___________ (11) ChinasSorrowitissoerraticanddangerous___________ (12) inasinglefloodithascausedamilliondeaths. FloodsharassedthegreatcivilisationoftheIndusRivervalley, andinadequatedrainageruinedmuch__________ (13) itsland. Today____________ (14) dominatesmanasitalwayshas___________ (15). Itspresencecontinuestogovernthelocationofhishomesandcities; itstempestuousvariabilitycankill ___________ (16) orhisherdsorhiscrops; itsrouteslinkhimto____________ (17) fellows; itsimmensevaluemayadd___________ (18) alreadydangerouspoliticalconflicts. Therearemanyexamples__________ (19) thisinour___________ (20) time.