Before leaving for the airport I have enough time to do something为什么live家ing?

问题描述:

Before leaving for the airport I have enough time to do something为什么live家ing?

这里是状语从句中的省略情况.
before leaving for the airport就等于before I leave for the airport.
由于从句中的主语跟主句中的主语都是I ,所以从句中的leave就跟主语I 构成了主动关系,那么就用直接省略成现在分词.