These groups mainly rely for instilling needed dispositions into the young upon the same sort of association which keeps the adults loyal to their group. instilling在这是什么意思？needed是过去分词作定语吗？upon又是什么意思》？
首先把句子改成：These groups mainly rely upon the same sort of association which keeps the adults loyal to their group for instilling needed dispositions into the young. 从而得到这个结构：rely upon sth for sth(依靠某物得到某物)。which keeps the adults loyal to their group是定语从句；instilling在这是“逐渐灌输”的意思；needed 是过去分词作定语修饰dispositions；rely upon等于rely on。大致意思是：这些组织主要依靠让成年人忠诚的那种入盟或入会方式来逐渐给年轻人灌输所需的性情。