all left to do is run 是否符合语法?是不是类似于what to do is a question?

应该是：
1 all （that is ） left to do is TO run
RUN是动词原形,前面要加上to,to run在这里是做句子的表语.
2 what to do（主语） is（系动词） a question（表语）.Children introduced to reading early develop strong verbal skills这句对么 introduced 是应被看成过去分词作定语还是Children （who are ) introduced to reading early develop strong verbal skills.一种省略形式，都可以？谢谢了Children introduced to reading early develop strong verbal skills这句对的。introduced 是过去分词作定语。Children （who are ) introduced to reading early develop strong verbal skills.-----可以。all that's left to do is run 符合语法么，谢谢了all that's left to do is run -------符合语法，ok.