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二者都表示“动作已经发生，区别在于：
(1)现在完成时强调这一动作与现在的关系，即对现在产生的结果、影响等，而一般过去时只表示过去的事实，不表示和现在的关系。
He has learned French for three years.他学法语已三年了。
He learned French for three years.他曾学过三年法语。
Who has taken my bag? I couldn't find it. 谁拿走了我的包?我找不着了!
He cleaned the house yesterday. 他昨天打扫过房间。
The room is clean, for he has cleaned it already. 房间很干净，因为他已经打扫过了。
(2)现在完成时不可与表示过去的时间副词连用，而一般过去时则可以。
He has done some washing yesterday. (F)
He did some washing yesterday. (T)
他昨天洗衣服了。