路基施工准备工作种，如地面有草而且有腐植土必须清除，因此在编制工程造价时，除计算清除表土项目外，还应计算除草项目。

Concerning the payment for the machines to be imported by us, we suggest that we make payment ______ three annual installments without interest.
A．byB．with
C．for D．on