Usage note
当用来表示时间或情况的特定时刻。
dāng lái bǎo shí huì jié shì qí miàn de kè mò。
When is used to indicate a specific moment in time or situation.
Context note
当常用于描述事件发生的时间点，如‘当太阳升起时’或‘当妈妈回家的时候’。
dāng cháng yòng yú miáo shì dǎn piàn fā shēn de shí jiān diǎn, rú ‘dāng tài yáng qǐ sù shí’ huò ‘dāng mā ma huí jiā de shí hou’。
When is often used to describe the time a certain event occurs, such as 'when the sun rises' or 'when mom comes home.'
5 examples
当太阳升起时，我们开始新的一天。
dāng tài yáng shēng qǐ shí， wǒ men kāi shǐ xīn de yì tiān。
When the sun rises, we start a new day.
当妈妈回家的时候，我正在写作业。
dāng mā ma huí jiā de shí hòu， wǒ zhèng zài xiě zuò yè。
When mom comes home, I was doing my homework.
当飞机起飞时，请系好安全带。
dāng fēi jī qǐ fēi shí， qǐng xì hǎo ān quán dài。
When the plane takes off, please fasten your seatbelt.
当你准备好后，我们出发吧。
dāng nǐ zhǔn bèi hǎo hòu， wǒ men chū fā ba。
When you are ready, we will set out.
当孩子们放学时，他们通常会去公园玩。
dāng hái zi men fàng xué shí， tā men tōng cháng huì qù gōng yuán wán。
When the children get out of school, they usually go to the park to play.
5 mini stories
当妈妈下班回家的时候，爸爸正在做饭。
dāng mā ma xià bān huí jiā de shí hòu， bà ba zhèng zài zuò fàn。
When mom comes home after work, dad is cooking.
当小明放学后，他通常会先做作业。
dāng xiǎo míng fàng xué hòu， tā tōng cháng huì xiān zuò zuò yè。
When Xiao Ming gets out of school, he usually does his homework first.
当天气变冷时，我们穿上了厚厚的棉衣。
dāng tiān qì biàn lěng shí， wǒ men chuān shàng le hòu hòu de mián yī。
When the weather turns cold, we put on thick coats.
当周末来临时，全家人会一起去郊游。
dāng zhōu mò lái lín shí， quán jiā rén huì yì qǐ qù jiāo yóu。
When the weekend arrives, the whole family goes for a trip together.
当妈妈在厨房忙碌时，小华帮忙洗菜。
dāng mā ma zài chú fáng máng lù shí， xiǎo huá bāng máng xǐ cài。
When mom is busy in the kitchen, Xiaohua helps wash vegetables.
Mini dialogue
当……的时候
A
当你回家的时候，记得洗手。
Dāng nǐ huíjiā de shíhou, jìde xǐshǒu.
When you come home, remember to wash your hands.
B
好的，妈妈。当我到家，我就洗手。
Hǎo de, māma. Dāng wǒ dàojiā, wǒ jiù xǐshǒu.
Okay, Mom. When I get home, I will wash my hands.
当心
A
当心！地上有水。
Dāngxīn! Dì shàng yǒu shuǐ.
Be careful! There's water on the floor.
B
谢谢你提醒我，我会当心的。
Xièxie nǐ tíxǐng wǒ, wǒ huì dāngxīn de.
Thank you for reminding me, I will be careful.
Related words and contrasts
similar
在……的时候
zài……de shíhou
at the time when...
A common pattern to express 'when' in a sentence.
similar
每当
měidāng
whenever
Used to say 'every time when' something happens.