Imagineyourbodyislikethehouseyoulivein.Everydayyourfamilycreatesrubbish.Therubbishbuildsupuntilitisputoutfortheweeklygarbagecollection.

      Nowsayyouputthreebagsofgarbageoutbutbecauseoneofthecollectorswasawaysickonlytwobagsarecollected.Youtaketheleftoverbaginsidetobeputoutagainnextweek.Thefollowingweekyouputonanotherthreebagsplustheleftoverbagfromlastweek.Butagainonlytwobagsarecollected.Imaginethiscycleisrepeatedoverthefollowingweeks.

      Thisisasimpledescriptionofwhathappenstoyourbodywhenyourkidneys(肾脏)don’tworkefficiently.Yourbodyisnotthoroughlyemptiedofwasteproducts.Otherareasofthebodysuchasbloodpressureandredbloodcellproductionareaffectedandtheinsidiousprocessthatmayleadtokidneyfailurebegins.

      It’snotuncommonforpeopletoloseupto90%oftheirkidneyfunctionbeforedevelopinganysymptoms.Theremaybenowarningsigns.Thismakesearlydetection(诊查)difficult.

      Kidney’smainjobistoremovetoxins(毒素)andunwantedwaterfromourblood.Everydayourkidneyscleananaverageof200litresofblood.Kidneyfailuremaybeagradualandsilentprocessgoingunnoticedbecausethereisnoapparentpain.

      Researchshowsthatmorethan25%ofthepatientsrequiringdialysis(透析)donotseeakidneyspecialistbeforetheyhavetodoso.Someriskfactorsforkidneydiseasesuchasageandgeneticmakeupareoutofourcontrol;howeversomechangesinlifestylemayhelppreventkidneydamage．Twomajorriskfactorsforkidneydiseasediabetes(糖尿病)andhighbloodpressurehavebeenontheriseoverthelastfewdecades．Bothconditionsarechieflyaffectedbybeingoverweightandnotgettingenoughexerciseswhicharethepotentialriskfactorsforthekidneydisease.

52.Theauthorgivestheexampleofthehouseweliveintoindicatethat_______.

   A.it’ssafeandharmlessforourbodytokeepsomewaste

      B.it’simportantforourbodytoemptythewasteintimeeveryday

      C.ourbodywillnotproduceanywasteifourkidneysworkefficiently

      D.itdoesn’tmattermuchifthewasteinourbodyisnotemptiedintime

53.Theunderlinedword“insidious”int