1-Review of the Grammar(Unit1-Unit3)By:Wu Qingyun Present Perfect Tense2-How long have you studied at this school?I have taught at this school since 2012.3-have/has+动词的过去分词不规则变化不规则变化现在完成时态现在完成时态规则变化规则变化4-rain lovestopstudy readcome seeleavebuygobe rained rained loved loved stopped stopped studied studied read read came come saw seen bought bought went gone left left was/were been规则变化（规则变化（-ed）不规则变化不规则变化Write down past tense and past participle of the following verbs.5-eat(ate,eaten)swim(swam,swu
