Usage note
可是用来表示转折，相当于英语中的but。
kě shì lái yòng biǎo zǐ zhé zhū ，相当 yú yǔ wén zhōng de but 。
可是 is used to indicate a contrast, similar to the English word 'but'.
Context note
可是常用于对话中，表示转折或对比。例如：我想去公园玩，可是妈妈说今天下雨了。
kě shì cháng yòng yú huà dá zhōng ，biǎo shí zhuǎn zhé huò duì bǐ 。例 如 ： wǒ xiǎng qù gōng yuán wán ， kě shì mā ma shuō jīntiān xia yǔ le 。
可是 is often used in conversations to indicate a contrast or comparison. For example: I want to go to the park to play, but my mom says it's raining today.
5 examples
我想吃冰淇淋，可是妈妈不让。
wǒ xiǎng chī bīng qí lín， kě shì mā ma bú ràng。
I wanted to eat ice cream, but my mom wouldn't let me.
我今天不想上学，可是爸爸坚持要我去。
wǒ jīn tiān bù xiǎng shàng xué， kě shì bà ba jiān chí yào wǒ qù。
Today I didn't want to go to school, but my dad insisted that I should go.
我想早点睡觉，可是电视节目还没结束。
wǒ xiǎng zǎo diǎn shuì jiào， kě shì diàn shì jié mù hái méi jié shù。
I wanted to go to bed early, but the TV show wasn't over yet.
我昨天去了图书馆，可是没借到书。
wǒ zuó tiān qù le tú shū guǎn， kě shì méi jiè dào shū。
Yesterday I went to the library, but couldn't borrow any books.
我想买玩具，可是妈妈说太贵了。
wǒ xiǎng mǎi wán jù， kě shì mā ma shuō tài guì le。
I wanted to buy a toy, but my mom said it was too expensive.
5 mini stories
小明想吃苹果，可是家里没有。
xiǎo míng xiǎng chī píng guǒ， kě shì jiā lǐ méi yǒu。
Xiaoming wanted to eat an apple, but there weren't any at home.
妈妈说今天要下雨，可是天气预报没说。
mā ma shuō jīn tiān yào xià yǔ， kě shì tiān qì yù bào méi shuō。
Mom said it would rain today, but the weather forecast didn't say so.
我想早点回家，可是朋友邀请我去玩。
wǒ xiǎng zǎo diǎn huí jiā， kě shì péng yǒu yāo qǐng wǒ qù wán。
I wanted to go home early, but my friend invited me to play.
我昨天想早点睡，可是电视节目还没结束。
wǒ zuó tiān xiǎng zǎo diǎn shuì， kě shì diàn shì jié mù hái méi jié shù。
Yesterday I wanted to go to bed early, but the TV show wasn't over yet.
我想买书，可是妈妈说太贵了。
wǒ xiǎng mǎi shū， kě shì mā ma shuō tài guì le。
I wanted to buy a book, but my mom said it was too expensive.
Mini dialogue
想出去玩
A
我想去公园玩。
Wǒ xiǎng qù gōngyuán wán.
I want to go to the park to play.
B
可是外面下雨了。
Kěshì wàimiàn xià yǔ le.
But it's raining outside.
做作业
A
作业很难吗？
Zuòyè hěn nán ma?
Is the homework difficult?
B
可是我会努力做完。
Kěshì wǒ huì nǔlì zuò wán.
But I will try my best to finish it.
Related words and contrasts
similar
但是
dàn shì
but
但是 also means 'but' and is slightly more formal. 可是 is very common in everyday spoken Chinese.
similar
不过
bú guò
however
不过 is another way to say 'but' or 'however', often used to introduce a milder contrast.