楼主误解了!
1、在这里to是不定式的符号,与后面的do构成不定式,不过to也可以是介词,此时后面就要接doing也就是动词-ing的形式,如look forword to doing sth.这里to就是介词.
2、结构：be going to do 一般将来时固定
不懂再问,
翻译小新!那beijing划线怎么问Where are you going to visit this winter vocation?What place are you going to visit this winter vocation？