Itisusefultoscience_______theearthasanobjectinspace.
A、toconsiderOnlya(n)________fewwereinvitedtothedancingparty.
EachyearintheUnitedStates,manyblackteenagers_______ofschool,eitherbecausetheycannotkeepuportheyhavetoworktosupporttheirfamily.
Asyoulikepopmusic,__________Ilikeliterature.
Humanbehaviorismostlyaproductoflearning________thebehaviorofanimalsdependsmainlyoninstinct.
Forthenewcountrytosurvive,________foritspeopletoenjoyprosperity,neweconomicpolicieswillberequired.
