在: where things are and where things happen

在 (zài) = to be at, to be in

On its own, 在 is a verb: "to be (somewhere)". Thing or person, then 在, then the place.

• 我的手机在桌子上。(Wǒ de shǒujī zài zhuōzi shang.)My phone is on the table.
• 你在哪儿？(Nǐ zài nǎr?)Where are you?

For "not there", use 不在 (bú zài):

• 老师不在办公室。(Lǎoshī bú zài bàngōngshì.)The teacher isn't in the office.

On the phone, 他不在 (tā bú zài) = he isn't here, he's out.

Places need 上, 里…

With an object as the place, add a position word after it: 桌子上 (zhuōzi shang) = on the table, 房间里 (fángjiān li) = in the room. Place names and place words (北京, 学校, 家) don't need it.

在 + place + verb: where an action happens

In English the place comes at the end: I work at a bank. In Chinese, the place phrase with 在 comes before** the verb:

• 我在银行工作。(Wǒ zài yínháng gōngzuò.)I work at a bank.
• 我们在饭馆吃饭。(Wǒmen zài fànguǎn chī fàn.)We eat at a restaurant.

Time first, then place, then the verb

When a sentence has both, the order is: who, when, where, what. The time word can also go at the very start.

• 他明天在图书馆学习。(Tā míngtiān zài túshūguǎn xuéxí.)He's studying at the library tomorrow.

One common exception: with 住 (zhù, to live), 在 usually comes after the verb: 我住在上海 (wǒ zhù zài Shànghǎi) = I live in Shanghai.

• 我住在上海。(Wǒ zhù zài Shànghǎi.)I live in Shanghai.

To ask "where", put 哪儿 after 在 (Question words: 什么, 谁, 哪儿, 几, 多少, 怎么). To say what exists in a place, use 有 instead (有: to have, there is).

Common mistakes

• 我工作在银行。 → 我在银行工作。The 在 phrase goes before the verb (住 is the exception).
• 我在家吃饭明天。 → 我明天在家吃饭。Time words come before the verb too, and before the place.
• 猫在桌子。 → 猫在桌子上。An object used as a place needs 上, 里 or another position word.
• Adding 是 for "I'm at home": the plain sentence is 我在家, because 在 is already the verb. (我是在家… exists, but it stresses something, as in 我是在家吃的 "it was at home that I ate".)