Hethoroughlyunderstoodthesociety__________.
A、Hethoroughlyunderstoodthesociety__________Itisusefultoscience_______theearthasanobjectinspace.
Theassociationis________toraisingfundstohelptheblind.
SinceWilliamhadbeenseriouslyillforseveralmonths,hisparentswereworriedabout________toreturntoschoolfull-time.
Whenworkersareorganizedintradeunions,employersfindithardtolaythem________.
Theoppositionleaders________thegovernmentfornottakingactionsooner.
