limit to 后面的to是介词所以跟doing,那变成被动为什么是be limited to do sth 具体原因

prefer doing to doing sth这个词组,to是介词所以后面接动名词,那么prefer后面为什么加动名 怎样分清动词后面是跟doing sth、to do sth、do sth? be surprised to do sth为什么be后面不跟doing? It's fun 后面是跟doing sth.还是跟to do sth. Be used to do sth Be used to doing sth 后者的to为何做介词? 为什么说be used to doing 的"to"是介词? why not后面是doing sth还是 to do sth be opposed to doing sth 是被动语态么? be accustomed to后面加do sth.还是doing sth? 这里的to不是做介词吗?那为什么后面跟doing? be limited to 里面的limited是形容词还是被动语态?举例如何用. see sb.do sth.的被动是be seen to do sth吗