请教语法问题
ThistrendbeganduringtheSecondWorldWar,whenseveralgovernmentscametotheconclusionthatthespecificdemandsthatagovernmentwantstomakeofitsscientificestablishmentcannotgenerallybeforeseenindetail.
句子分析：
第一、句子可以拆分为三段：ThistrendbeganduringtheSecondWorldWar,whenseveralgovernmentscametotheconclusion/thatthespecificdemandsthatagovernmentwantstomakeofitsscientificestablishment/cannotgenerallybeforeseenindetail.
第二、句子的结构：
1)主干结构是主句+when引导的时间状语,when=atthattime当时,那时.
2)第一个that从句是主句宾语theconclusion的同位语.
3)thatagovernmentwantstomakeofitsscientificestablishment是定语从句中的主语从句
4)cannotgenerallybeforeseenindetail是宾语从句的谓语.
完整的译文：
这种趋势始于第二次世界大战期间,当时一些国家的政府得出结论：政府向科研机构提出的具体要求通常是无法详尽预见的.
【thatagovernmentwantstomakeofitsscientificestablishment是定语从句中的（主语从句）是什么意思呢,定语从句补全是不是agovernmentwantstomakeofthespecificdemandsitsscientificestablishment?】