Ifyouhavedifficultylocatingaparticularbook，pleaseaskourlibrariansfor___(assist).
Thisessayisstilltoolong.I’llhaveto___(short)itbyoneortwopages.
TheUnitedStatesisacountry_(advance)inscienceandtechnology
Studentsshould（）theirowninterestsaswellasdotheirschoolwork.
自由竞争资本主义时期，资本主义国家对外经济关系的主要内容是（）
