A. after B. before C. on
A. 售前服务 B. 售中服务 C. 售后服务
A. never B. seldom C. often
A. sellers B. buyers C. workers
A. sellers B. workers C. users
A. of B. apart C. before
A. in B. out C. back
A. important B. not important C. unnecessary
A. 目标 B. 谈判 C. 讨价还价