一、时态讲解：现在完成时 （1）构成：现在完成时由助动词have + 过去分词构成，助动词have 有人称和数的变化。第三人称单数用has，其余用have. 现在完成时的否定式直接在助动词后面加上not、疑问式是把助动词提到主语之前。以study 为例，其否定式、疑问式和简单回答形式如下： 否定式 疑问式 I have not (haven’t) studied… . Hav e I stu died…? You hav e not (hav en’t) stu died…. Hav e y ou stu died…? He has not (hasn’t) stu died…. Has he stu died…? 否定疑问式 简单回答（肯定/否定） Hav e I not (Hav en’t I) stu died…? Yes, y ou hav e. No, y ou hav en’t. Hav e y ou not (Hav en’t y ou ) stu died…? Yes, I hav e. No, I hav en’t. Has he not (Hasn’t he) stu died…? Yes, he has. No, he hasn’t. （2）用法： 1）现在完成时通常表示在说话之前已经完成的动作或存在的状态。说话人强调的是该动作或状态对现在的结果或影响。 My daughter has just gone out. 我女儿刚出去。 I’m sure we’ve met before. 我肯定我们以前见过面。 She has arrived. 她到了。 2）表示持续到现在的动作或状态，往往和包括现在在内的表示一段时间的状语连用，如recently, already, just, lately, for…, since…,yet 等。如： I haven’t heard from her these days. 这些日子我没有收到她的信。 We haven’t seen you recently. 最近我们没有见到你。 They have been away for two years. 他们离开已经两年了。 She has been with us since Monday. ★注意： a) since 和 for 的区别 since 后接时间点，如 1993，last term, yesterday, the time I got there for 后接一段时间，表示“长达多久”，如 ten years, a while, two days 等。 Exercise: 用 since 和 for 填空 1. Jim has been in Ireland ______ Monday. 2. Jill has been in Ireland ______ three days. 3. His aunt has lived in Australia ______15 days. 4. Mary is in her office. She has been there ______ 7 o'clock. 5. India has been an independent country ______1974. 6. The bus is late. The...
