「了」的两张脸

我吃了饭。     I ate.            那件事做完了
他走了。       He has left.      现在不一样了
下雨了。       It's raining.     状态变了

那件事 → 过去式 现在变了 → have / has …

最容易翻车

❌ I have gone to Beijing yesterday.
✅ I went to Beijing yesterday.

yesterday / last week 一出现 → 锁死过去式。

动手

这本书我看了。（不用再买）

✅ I've read this book.

我昨天吃了三个苹果。

✅ I ate three apples yesterday.

天黑了。

✅ It's dark now.

顺手记

我去了北京。   I went to Beijing.        那件事
我去过北京。   I've been to Beijing.     这辈子

——下一课：「在」。