by the piece 
论件
- 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 - We pay our workers by the piece here, not by the time they take to do the work.
我们依件支付我们的员工,而非依他们花在工作上的时间。 - The baggage arrived piece by piece. One day a trunk came; another day, a bedroll. Every afternoon they went to the
行李陆续运来,今天来个箱子,明天来个铺盖,他们每天下午,得上汽车站去领。
by the piece[ adv ]
one piece at a time
<adv.all>
she sold the plates by the piece