For / since / ago

For、since 和 ago 都和時間有關，但用法各不相同：

例如：今天是星期四，阿蘭星期一到了河內。同一件事可以有三種說法：

• Lan has been in Hanoi for three days.

  阿蘭在河內已經三天了。

• Lan has been in Hanoi since Monday.

  阿蘭從星期一起就在河內了。

• Lan arrived in Hanoi three days ago.

  阿蘭三天前到了河內。

💡兩個常見陷阱：中文“從 2019 年開始（到現在）”是 since 2019——from 後面通常要接 to/until（from 2019 to 2022）；“兩年前”（從現在往回算）是 two years ago，不是 before two years。

For 回答 How long?，可以用於任何時態，不只是現在完成時。

• I've had this phone for three years.

  這部手機我已經用了三年了。（現在還在用）

• We lived in Hue for two years, and then we moved to Saigon.

  我們在順化住了兩年，然後搬到了西貢。（已經結束 → 一般過去時）

• I'm staying with my cousin for a week.

  我要在表哥家住一個星期。

• 用在現在完成時的否定句中：I haven't seen her for years。美式英語也常用 in：I haven't seen her in years。
• for + 一段時間（for two hours）和 during + 事件或時期（during the film、during the summer）不同：during 說的是什麼時候，不是多長時間。
• for ages（口語）= 很久很久：I haven't been to the cinema for ages。

Since 給出起點——某一天、某一年、某件事——動作從那時一直持續到現在。所以主句通常用完成時（have/has + V3 或 have/has been + -ing）。

• My dad has worked at the hospital since 2015.

  我爸爸從 2015 年起就在這家醫院工作。

• I haven't eaten anything since this morning.

  我從早上到現在什麼都沒吃。

• Binh has played football since he was little.

  阿平從小就踢足球。（since + 一般過去時從句）

• It's been two years since I last saw Minh.

  我上次見阿明已經是兩年前了。

It's been (= It has been) + 一段時間 + since + 一般過去時 這個句型在口語中很常見。英式英語也說 It's two years since…，意思相同。

Ago 放在一段時間的後面，從現在往回算。它指的是已經結束的時刻，所以和一般過去時連用，不用現在完成時。提問用：How long ago…? 或 When…?

• Hung moved to Hanoi three years ago.

  阿雄三年前搬到了河內。

• How long ago did you start this job? — About six months ago.

  你多久以前開始做這份工作的？——大約六個月前。

• I called her ten minutes ago, but she didn't answer.

  我十分鐘前給她打了電話，但她沒接。

💡Ago 從現在往回算；before 從過去某個時刻往回算：She left Hanoi in 2020. She had moved there two years before（= 2018 年）。單獨使用時，before 意思是“以前”：I've never been here before。

選時態之前先問自己：這件事還在繼續，還是已經結束了？

同樣的資訊可以從一種句型換成另一種：

• I bought this bike two years ago. → I've had it for two years.

  這輛腳踏車我是兩年前買的。→ 我已經騎了兩年了。（bought → have had，不是 have bought）

• Minh started learning the guitar in 2023. → He's been learning it since 2023.

  阿明 2023 年開始學吉他。→ 他從 2023 年起一直在學。

• The last time I saw Hoa was in May. → I haven't seen Hoa since May.

  我最後一次見阿花是在五月。→ 從五月到現在我都沒見過阿花。

• ✗I have studied English since five years.

  ✓I have studied English for five years.

  five years 是一段時間 → for。

• ✗I have lived here for 2019.

  ✓I have lived here since 2019.

  2019 是起點 → since。

• ✗We met each other before two years.

  ✓We met each other two years ago.

  “……以前”= 一段時間 + ago。

• ✗I have seen that film two weeks ago.

  ✓I saw that film two weeks ago.

  ago 指已經結束的時間 → 一般過去時。

• ✗I live here since 2020.

  ✓I have lived here since 2020.

  用 since 時主句要用完成時。

• ✗I'm waiting for an hour!

  ✓I've been waiting for an hour!

  說到現在為止持續了多久，用完成時，不用現在進行時。