高三英语题目关于语法的,求详细解释

1.with引导的独立主格结构作状语
独立主格是his son,
考察动词与独立主格的语法关系（注意,不是逻辑关系,可能会有被动语态）
〉主谓-现在分词
〉动宾-过去分词
至于 having been enrolled,从来没有看到过!
记住,考非谓语的选择题里一旦出现含有/having been/的选项,99.9%是错的,还有0.1%我没见过.
举例-He walked in with his leg transplanted,能理解为什么不是/with his leg having been transplanted/不?因为累赘太多了.
2.than引导的比较状语从句特殊语序(这里和省略有毛关系啊啊啊?!)
当than引导比较状语从句,并且从句主语不是代词（I,you,she,he,they,it）时,把从句谓语助动词提前,没有助动词时提前/do/.
举例-Ichthyosaurs(鱼龙) had a higher chance of being preserved than did terrestrial creatures（陆地生物） because,as marine animals,they tended to live in environments less subject to erosion.
鱼龙比起陆地生物有着更多的机会被保存下来,因为作为海洋动物,它们趋向于居住在更少受侵蚀影响的环境中.
3.这是唯一一点楼上答对的.
把with ___ 移动到最后你瞬间明白了.
BTW,/ it/指代/being the parent of a child with special needs /.