by the piece

副词 by the piece:

1. one piece at a time
   同义词：one by one

1. Payment for labor or services to a worker, especially remuneration on an hourly, daily, or weekly basis or by the piece.
   工资为劳动或服务伏给一个工人的报酬，尤指按小时、天数或周给或按工作量给