是…的: stressing details of a past event
句型 / sentence patterns (是…的)
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
Subject + (是) + when / where / how / with whom + Verb + 的
When you already know an action happened and want to talk about a detail (when? where? how? with whom?), frame that detail with 是…的.
你是什么时候来的？(When did you get here?) 我是坐飞机来的 (I came by plane).
是 can drop in affirmative sentences, but 的 stays. Negative: 不是…的: 我不是一个人去的.
With an object, 的 often goes before the object: 我是在北京学的中文.
Examples
你是什么时候来中国的？
Nǐ shì shénme shíhou lái Zhōngguó de?When did you come to China?
我是二〇一九年来的。
Wǒ shì èr líng yī jiǔ nián lái de.I came in 2019.
我们是坐火车去的。
Wǒmen shì zuò huǒchē qù de.We went by train.
我不是一个人去的，是跟朋友一起去的。
Wǒ bú shì yí ge rén qù de, shì gēn péngyou yìqǐ qù de.I didn't go alone, I went with friends.
你在哪儿学的中文？
Nǐ zài nǎr xué de Zhōngwén?Where did you learn Chinese?
Common mistakes
✗ 我是坐飞机来了 → ✓ 我是坐飞机来的 (是…的, not 了).
是…的 is only for past events: ✗ 我明天是坐飞机去的.