Weregretto________thatitmaynotbepossibletodealwitheveryrequest.
A、putoffHumanbehaviorismostlyaproductoflearning________thebehaviorofanimalsdependsmainlyoninstinct.
Whenworkersareorganizedintradeunions,employersfindithardtolaythem________.
________tothepapersisrestrictedtoDefenseDepartmentpersonnelonly.
Idon'tknowhowwecanmake________onthetimetableforanymorecourses.
Forthenewcountrytosurvive,________foritspeopletoenjoyprosperity,neweconomicpolicieswillberequired.
