Great changes have taken place since you left.这句话是个什么从句?省略了什么关系连词?省略的关系连词加在哪?

问题描述:

Great changes have taken place since you left.这句话是个什么从句?省略了什么关系连词?省略的关系连词加在哪?

时间状语从句.
自从你离开后,这里发生了很大的变化.
Great changes have taken place since the time when you left.