The Salk vaccine is a major factor in the fight to eradicate polio.
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Thefearofsmallpox,whichterrorizedtheeighteenthcentury,hasnoanalogy(likeness)today.
Alligatorsstillexistinsomeofthedank潮湿swampsandbayous小海湾ofAlabama'scoastalregions.
Whencarbonisaddedtoironintheproperproportions,theresultissteel.
Communicationisoneofthemostimportantbondsthatholdculturalsystemstogether.
In1861itseemedinevitablethattheSouthernstateswouldbreakawayfromtheUnion.