一、规则:在通常情况下 ago 只与过去时连用,而不与现在完成时连用。因为ago指的是多久以前的过去时间,而现在完成时表示的动作虽然发生在过去,但它强调的是与现在的联系或对现在的影响,因此两者不能用在一起。如:我两个月前见过他。误:I have seen him two months ago. 正:I saw him two months ago.

 

二、特例:但是,有时为了行文的需要或使句子生动,ago可用于类似以下这样的句子:I had thought that he had died at least 20 years ago. 我原以为他至少在< ago. years 20 least at died had he that>20年前就已经去世了。