请教一句英文国贸合同中的句子,多谢.Thiscontract,includingappendices,constitutesthecompletecontractofthepartieswithrespecttothesubjectproductreferredtoandsupersedesallpriorornegotiations,promises,covenants,agr

Question

请教一句英文国贸合同中的句子,多谢.
This contract, including appendices, constitutes the complete contract of the parties with respect to the subject product referred to and supersedes all prior or negotiations, promises, covenants, agreements or representations, all of that may have become merged and finally integrated into this contract. This contract may not be amended, modified or supplemented except by an instrument in writing and executed by the parties.

Answer 1

本合同及其附件,怀着对相关产品的敬意,构成一份完整的双方（也许是几方,parties,指谈判方）合约书.先前的一切协商,承诺,契约,协定或声明都可能已融入这份合约,（从合约生效起,）以此合约为准.此合约的修改或补充必须由当事方的书面文件执行.
不知道合同要怎么写才准确,但是意思保证没有错.括号里的是原文没有直接说,但是句意如此,就写下来保持句子通顺的,括号外的全部是原文翻译,除句子语序必要调动外,没有其它改动.