6 A few art collectors Tames Bowdoin III of Boston，William Byrd of Virginia，and the Aliens 夫妇 and Hamiltons 夫妇 of Philadelphia introduced European art traditions to those colonists
Privileged特权 to visit their galleries，especially aspiring 抱负的 established in their respective communities社区 the idea of the value of art and the need for institutions机构 devoted to its encouragement.
(A few art collectors…introduced European art traditions to those colonists…and established…the idea…and the need…为句子主干)
几个艺术收藏家，波士顿的詹姆士·鲍德温三世、弗吉尼亚的威廉·白尔德租费城的阿里昂夫妇以及汉密尔顿夫妇将欧洲艺术传统介绍给那些被特许参观他们画廊的殖民者，尤其是有抱负的艺术家们，并在他们各自的社区形成了艺术有价值和需要设立机构以鼓励其发展的观念。
分析：
此长句全为主句，没有从句。整句只能找主干与修饰部分，不能分 art collectors introduced traditions to those colonists and established in the idea of the value of art and the need for institutions
修饰成分：
(1)几个人名并列：Tames Bowdoin III of Boston，William Byrd of Virginia，and the Aliens and Hamiltons of Philadelphia
(2)非谓语动词后缀修饰名词：privileged to visit their galleries修饰colonists
devoted to its encouragement修饰institutions
(3)插入语 ，especially aspiring artists.
(4)介词短语修饰谓语动词：in their respective communities 修饰 established