since two day ago和two day ago还是for two day相同?怎么区分

问题描述:

since two day ago和two day ago还是for two day相同?怎么区分

since 后面接具体的时间点,for接时间段,一般用于完成时态中。
two days ago只两天前,一般出现在一般过去时中。

two day ago 是一般过去式,另外两个是现在完成时,

since two days ago相当于for two days,常用于现在完成时态中two days ago 两天前,用于一般过去时.如The fish died two days ago .The fish has been dead since two days ago.The fish has been dead for two days....