英语翻译
原文:Thedecisionwasmadetoerronthesafesidebecauseacompletedevelopmentsystemspecifictothechosenpartwasnecessary,andtheprojectbudgetdidnotpermitasecondsuchsystemtobepurchasedshouldthefirstproveinadequate.
前一句还好理解,后一句里面的那个should的主语是谁?