once there was a king who had three sons .是什么句式?所关系到什么语法?详解一下.
问题描述：
once there was a king who had three sons .是什么句式?所关系到什么语法?详解一下.
谢谢!
答
Once 表示曾经,然后是一个There be句型（there was a king),who had three sons 是定语从句修饰king.