现在完成时精讲
一、结构
肯定式： have/has + 过去分词 否定式： have/has + not + 过去分词 疑问式： Have/Has + 主语 + 过去分词？
二、用法
用法1： 过去发生的动作对现在有影响
I have lost my key.（我现在没钥匙了）
用法2： 从过去持续到现在的动作
She has lived here for 10 years.（现在还住在这里）
三、标志词
| 标志词 | 含义 | 例句 |
|---|---|---|
| already | 已经（肯定句） | I have already finished. |
| yet | 还没（否定/疑问句） | Have you finished yet? |
| ever | 曾经 | Have you ever been to Beijing? |
| never | 从未 | I have never seen that movie. |
| just | 刚刚 | He has just left. |
| since | 自从 | since 2020 / since I was born |
| for | 持续 | for three years |
四、与一般过去时的区别
一般过去时：强调过去的动作，与现在无关 ✅ 现在完成时：强调过去的动作与现在的联系 ✅
- I saw the movie yesterday.（只是说昨天看了）
- I have seen the movie.（强调我现在知道剧情了）