TheSalkvaccineisamajorfactorinthefighttoeradicatepolio.
Favorablepoliciesare___________toencourageemployees'professionaldevelopment.
Urbanrenewalprogramsstrivetoupgradeareasthatarebecomingslums.
In1861itseemedinevitablethattheSouthernstateswouldbreakawayfromtheUnion.
关于大众传媒对人类行为的影响，下列表述正确的有()。
