Once harm is done to the environment,it takes years to have the system recovered.这是什么从句?哪是从句,哪是主句?

分类: 作业答案 • 2021-12-20 03:11:23

问题描述：

Once harm is done to the environment,it takes years to have the system recovered.
这是什么从句?哪是从句,哪是主句?

答

主语从句，逗号前面的是主语，it代替

答

逗号前是从句,后面是主句
once引导条件状语从句