Subject + 在 + Verb
Reach for 在 + Verb when you want to say something is happening right now — 'I'm watching TV,' 'they're singing,' 'the cat is sleeping.' It's the most common way to mark an ongoing action in Mandarin, equivalent to English '-ing' in the present continuous. Drop 在 directly before the verb; no other tense markers needed. You can strengthen it with 正在 for 'right at this moment' or soften it by ending the sentence with 呢, but the bare 在 + Verb is the everyday default for beginners.
Structure
[SUBJECT] 在 [VERB] ([OBJECT])
zài [VERB]...
How to Think About It
在 here is a time-marker, not the location word 'at.' It freezes the camera on the verb and says 'this is happening now.' Don't confuse it with the location 在 (我在家 = I'm at home), which sits between subject and a place noun. With a verb after it, 在 always means 'in the middle of doing.' Negate with 没在 (没在看 = not currently watching), not 不在.
Examples
我在看书。
Wǒ zài kàn shū.
I'm reading a book.
他们在打篮球。
Tāmen zài dǎ lánqiú.
They're playing basketball.
妈妈在做饭。
Māma zài zuò fàn.
Mom is cooking.
Common Mistake
Learners pile 了 onto a 在 + Verb sentence ('我在看了电视'), trying to mark completion. 在 + Verb signals an ongoing action, which is incompatible with 了 (the completion marker). Pick one or the other depending on whether the action is in progress or already done.
我在看了电视。
我在看电视。
Don't Confuse With
正在 + Verb
Use 正在 to stress 'right at this very moment.' Plain 在 is enough for any ongoing action; 正在 just adds urgency.
Verb + 着
Use 着 for a sustained STATE (门开着 = the door is open). 在 + Verb is for an ACTION in motion. 'Door is open' vs 'someone is opening the door.'
在 + Place
Use 在 + place noun (我在家) to say WHERE someone is. 在 + verb says WHAT they're doing right now. Same character, different jobs depending on what follows.
Practice
Fill in the blank: 弟弟 ___ 写作业。
Show answer
在
Fill in the blank: 我们在 ___ 电影。 (watching)
Show answer
看
Arrange: 在 / 老师 / 课文 / 读
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老师在读课文。
Translate: The children are singing.
Show answer
孩子们在唱歌。
Write one sentence about what you're doing right now using 在.
Show answer
我在学中文。
Hear It in Real Episodes
This pattern appears in 3 Fluentide episodes: