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XX年12月英语四级仔细阅读满分练习题xx年12月英语四级仔细阅读满分练习题 There isevidence thatthe usualvariety ofhigh blood pressure is,in part,a familialdisease.Since familieshave similargenes aswell assimilar environments,familial diseasescould bedue to shared geicinfluences,tosharedenvironmental factors,or toboth.For someyears,the roleof one environment factormonly sharedby families,namely dietarysalt i.e.,sodium chloride,has beenstudied atBrookhaven NationalLaboratory.These studiessuggest thatlong excesssalt intakecan leadto high bloodpressurein manand animals.Some individuals,however,and somerats consumelarge amountsof saltwithout developinghighbloodpressure.No matterhow strictlyall environmentalfactors werecontrolled inthese experiments,some salt-fed animalsnever developedhypertension whereasa fewrapidly developedvery severehypertension followedby earlydeath.These markedvariations wereinterpreted toresult fromdifferences ingeic const...。