Centuriesagomandiscoveredthatremovingmoisturefromfoodhelpstostoreitandthattheeasiestwaytodothisistoexposethefoodtosunandwind.

Allfoodsincludingwater—cabbageandotherleafvegetablescontainsasmuchas93%waterpotatoesandotherrootvegetables80%lean(瘦的)meat75%andfishanythingfrom80%to60%dependingonhowfattyitis.Ifthiswaterisremovedtheactivityofthebacteriawhichcausefoodtogobadiscontrolled.

Nowadaysmostfoodsaredriedmechanically.Theconventionalmethodofsuchdehydration(脱水)istoputfoodinchambers(室)throughwhichhotairisblownattemperatureofaboutll0'Catentrytoabout43'Catexit.Thisistheusualmethodfordryingsuchthingsasvegetablesmincedmeatandfish.

Liquidssuchasmilkcoffeeteasoupsandeggsmaybedriedbypouringthemoveraheatedsteelcylinder(圆筒)thenputthemintoachamberthroughwhichacurrentofhotairpasses.Inthefirstprocessthedriedmaterialcomesofftheroller(滚筒)asathinfilmwhichisthenbrokenupintosmallthoughstillrelativelyflakes(薄片).Inthesecondprocessitfallstothebottomofthechamberassmallpowder.Whererecognizablepiecesofmeatandvegetablesarerequiredasinsouptheingredients(成分)aredriedseparatelyandthenmixed.

Driedfoodstakeuplessroomandweighlessthanthesamefoodpackedincansor

frozenandtheydonotneedtobestoredinspecialconditions.Forthesereasonsthey

areinvaluabletotheclimbersexplorersandsoldiersinbattlewhohavelittlestorage

space.Theyarealsopopularwithhousewivesbecauseittakessolittletimetocook

them.

小题1:Itcanbeinferredfromthepassagethat________.A．therattierfishcontainasmuchwaterastheleanoneB．therattierthefishisthemorewateritmaycontainC．afattyfishholdslesswaterthanaleanoneD．thewatercontentoffishhasnothingtodowiththecontentoftheirfat小题2:Theunderlinedword"conventional"inParagraph3canmostprobablybereplacedby_________.A．particularB．scientificC．usualD．special小题3:Whichofthefollowingstat