三年前？正确表述应该是3 years ago解析：before和ago都能表示在一段时间以前，但是二者的内涵和具体用法有明显的区别：1. before表示从过去或将来某一时间算起多少时间以前，由于与这一时间状语连用的行为先发生在过去或将来某一时刻之前，因此往往出现在过去完成时态或将来完成时态中。例如：① I called him up last night， but his mother told me he had left for Wuhan two days before.② She said that she had married him five years before.2.如果不具体表明多
