The PresentThe PresentPerfect Tense 1. 现在完成时态表示过去发生的动作对现在造成的影响或结果 Our teacher has left. We have studied English. I have already finished the homework. He has had his lunch. He has become a doctor.have/has+ 过去分词 2. 某个动作从过去已经开始 , 一直持续到现在 , 还有可能持续到将来 . 动作的持续性要通过一段时间来表示 .一段时间的表达方法有两种 :for: + 一段时间 for a year for two weeks for three yearsSince 过去的某一时刻 , since nine since last week 一般过去时态的时间状语从句 since you came since you got home.注意 :for 和 since 所引导的时间状语都表示一段时间 .He has been away since last week.He has been away for one week.对划线部分提问都用 How long The Past The Past Perfect TensesNew 现在完成时：现在完成时：助动词 have have // has has + 过去分词过去完成时：过去完成时：助动词 hadhad + 过去分词 构成？ 我认识他三年了。我认识他三年了。 I have known him for I have known him for three years. three years. I had known him when I I had known him when I was a student.was a student.我当学生时，就已经认识我当学生时，就已经认识他了。他了。had knownhad known have knownhave known waswas 我已经做完作业了。我已经做完作业了。表示在说话时已经做完。表示在说话时已经做完。I I have finishedhave finished my home- my home-work.work. 在六点以前，我就已经在六点以前，我就已经完完 成作业了。成作业了。ByBy six o’clock, I six o’clock, I had had finishedfinished my homework. my homework. 表示在过去的某一段时间表示在过去的某一段时间（（ six o’clock six o’clock 以前）以前）已经已经做完作业，与现在无关。做完作业，与现在无关。 他们已经吃过早饭了。他们已经吃过早饭了。 在他们到旅馆之前他们在他们到旅馆之前他们已已 经吃过早饭了。经吃过早饭了。They They havehave already already hadhad breakfast.breakfast.They They hadhad already already had had breakfast breakfast beforebefor...
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