TheSalkvaccineisamajorfactorinthefighttoeradicatepolio.
A、completelydestroyFormulatedin1823,theMonroeDoctrineassertedthattheAmericaswerenolongeropentoEuropeancolonization.
Thefirstpaperwasmadefromthebarkofthemulberrytree.
Solidgeometryhasenabledastronomerstocalculatethepositionsoftheheavenlybodiesrelativetooneanother.
Peoplewhodonotsleepenoughtendtobecomeirritable.
Communicationisoneofthemostimportantbondsthatholdculturalsystemstogether.
