five years before 用法和five years ago的区别

问题描述:

five years before 用法和five years ago的区别

用before时句子要用完成时,ago只能用于一般过去式

ago表示从现在起,若干时间之前,常与一般过去时连用,不能与完成时连用。before 是从过去某一时刻起,若干时间以前,常与过去完成时连用

before 以过去某时为起点的.之前
ago 以现在为起点的.之前
he told me that he had finished his university five years before.(现在算起,毕业六年了)
he tells me that he has been in the factory five years ago(入厂五年了)
供参考.