我很忙，故不能参加你的聚会。
wǒ hěn máng ， gù bùnéng cānjiā nǐde jùhuì 。
I am very busy, so I cannot attend your gathering.
天气不好，故我们决定不出门。
tiānqì bùhǎo ， gù wǒmen juédìng bù chūmén 。
The weather is bad, so we decided not to go out.
他没有完成作业，故老师把他叫去了。
tā méiyǒu wánchéng zuòyè ， gù lǎoshī bǎ tā jiào qùle 。
He didn't complete the homework, so the teacher called him in.