🎯 这节课你会学到
- 现在完成时的结构：have / has + 过去分词
- 它和一般过去时的本质区别（专升本最爱考）
- since 和 for 的区别
- 标志词全家桶
📖 讲解
1. 结构：have / has + 过去分词
| 人 | 结构 | 例句 |
|---|---|---|
| I / you / we / they | have + 分词 | They have finished the work.（他们已经完成工作了。） |
| he / she / it | has + 分词 | She has lost her keys.（她把钥匙弄丢了。） |
过去分词哪来的？两种来源：
- 规则动词：和过去式长得一样（watch → watched → watched；study → studied → studied）
- 不规则动词：背第三种形态（go → went → gone；see → saw → seen；do → did → done；eat → ate → eaten）
2. 它到底什么意思？（理解了就不难）
现在完成时 = 过去的动作，对现在有影响。
- I have lost my keys. → 重点不是「过去丢了」，而是「所以现在我手里没有钥匙」（影响还在）
- I lost my keys yesterday. → 只陈述昨天丢了这件事（+ 具体过去时间，用一般过去时）
一句话分辨：有具体过去时间（yesterday / in 2020 / last week）→ 一般过去时；没有具体时间、强调结果影响到现在 → 现在完成时。
3. since 和 for（必考）
| 词 | 接什么 | 例句 |
|---|---|---|
| since | 时间点（2010 年、那时起） | I have lived here since 2010. / since he was a child |
| for | 时间段（十年、多久） | I have lived here for ten years. |
口诀：since 点，for 段。看见这两个词 → 闭眼选现在完成时。
4. 标志词全家桶（见词选完成时）
- already 已经（肯定句）：I have already finished.
- yet 还（否定/疑问）：Have you finished yet? / I haven’t finished yet.
- just 刚刚：She has just left.
- ever / never 曾经 / 从未：Have you ever been to Beijing? I have never seen the sea.
- so far 到目前为止 / in the past few years 在过去几年里
⚠️ 零基础最容易犯的错
- has / have 用反：❌ She have gone. → ✅ She has gone.
- 不规则分词写错：❌ I have went. → ✅ I have gone.（went 是过去式，分词是 gone）
- 句子里有 yesterday 还用完成时：❌ I have seen him yesterday. → ✅ I saw him yesterday.
- for / since 接反：❌ for 2010 / ❌ since ten years → ✅ since 2010 / for ten years
📝 随堂小练
- She ____ (live) here since 2015.
- I ____ (finish) my homework already.
- ____ you ever ____ (be) to Shanghai?
- 改错：He has went to the library.
- 选时态并填空：We ____ (know) each other for ten years.
答案（先自己写！）
- has lived（since → 完成时；she 配 has）
- have finished（already → 完成时；I 配 have）
- Have you ever been…?（be 的分词是 been）
- went ❌ → gone（has 后接过去分词）
- have known（for + 时间段 → 完成时；know 的分词是 known）
➡️ 下一课预告
第 9 课：六大时态大合并——一张总表 + 12 题混练，检验你前六课的成果。