为自己加油

改进题：IN WITNESSTH WHEREOF the parties hereto have executed this Contract by their authorized representatives as of the date first above written.

译文：兹特由双方授权的代表，以首开的上述日期和签署的本合同为据。

改进的译文：兹特由双方授权的代表，于上述首开日期和签署本合同为据。