This is the first time in their lives to ski on the Apls.划分句子成分

问题描述:

This is the first time in their lives to ski on the Apls.划分句子成分

这是个主系表结构的扩充.
this主语,is系动词,the first time (他们生命中的第一次)是表语,in their lives时间状语,to ski on the Apls是to do结构作the first time in their lives的补语,补充说明第一次干什么.
不懂追问~to ski做什么成分?谢谢the first time to do sth. 第一次干某事。成分的话:就是to do 结构作the first time的后置定语,进行补充说明。