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
答
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。