Insomeschoolschildrenwhoprefertoreadbooksratherthan________footballbecomesocialoutcasts(被抛弃者).
EachyearintheUnitedStates,manyblackteenagers_______ofschool,eitherbecausetheycannotkeepuportheyhavetoworktosupporttheirfamily.
Itisusefultoscience_______theearthasanobjectinspace.
Thestudentfoundthenovel_______.Itprovidedhimwithsomuchinformationaboutthesubject.
________,Johnhasbeentoseveralforeigncountries.