英语语法问题-请问这里为什么是had to而不是have to?

问题描述:

英语语法问题-请问这里为什么是had to而不是have to?
There are many places that I like.If I had to choose one place,I would like to tell you about Government Square.

虚拟语气,对现在的虚拟:从句动词用did形式,主句用 would +do