Translation of "contractor" into Chinese

I can't calculate the final cost without first discussing it with our contractors.

不先與我們的承包商討論的話我無法計算出最後的費用。

This document defines the amount to be paid to the contractor for the work performed.

它确定了应为已完成的工程向承包人支付的数额。

The masks and suits were supplied to the contractors’ staff on site.

防毒面具和防护服务提供给承包方在工地的工作人员。