定义 / 说明
英语有多种方式表达过去反复发生的动作或状态。used to 常用于“过去习惯”或“过去状态（现在不再如此）”。would 可用于叙事中的过去重复动作，但通常不用于过去状态。past simple 在语境能体现重复时也可表达过去习惯。正确选择能更清楚表达你说的是旧习惯、旧状态，还是一连串过去事件。
关键规则
- used to + base verb：表示过去习惯和过去状态：I used to live in Leeds.
- would + base verb：表示过去反复动作（常见于故事）：Every summer we would camp by the lake.
- would 通常不用于过去状态（如一般意义上的 be, have, know, live）。
- Past simple 也可表示过去习惯：When I was a child, I played outside every day.
- used to 常暗示“与现在形成对比”。
例句
- I used to play chess after school. - 我以前放学后常下棋。
- On Sundays we would visit Grandma. - 以前每到周日我们都会去看奶奶。
- She used to have long hair. - 她以前留长发。
- When we were children, we played in the street every evening. - 我们小时候每天傍晚都在街上玩。
- My father used to work nights. - 我父亲以前常上夜班。
常见错误
- ❌ I would live in Rome when I was a child. -> ✅ I used to live in Rome when I was a child.
- ❌ She used to went there every day. -> ✅ She used to go there every day.
- ❌ We would be very shy at school. -> ✅ We used to be very shy at school.