Clause A,于是 + Clause B
于是 is a conjunction meaning "and then," "so," or "thereupon," used to connect two clauses where the second is a natural consequence or follow-up of the first. It indicates a sequential and often causal relationship between events. It is common in narrative and storytelling.
下课了,于是我们一起去吃饭。
Xiàkè le, yúshì wǒmen yìqǐ qù chīfàn.
Class was over, so we went to eat together.
天突然下雨了,于是他决定打车回家。
Tiān tūrán xiàyǔ le, yúshì tā juédìng dǎchē huíjiā.
It suddenly started raining, so he decided to take a taxi home.
她觉得无聊,于是打开手机看视频。
Tā juéde wúliáo, yúshì dǎkāi shǒujī kàn shìpín.
She felt bored, so she opened her phone to watch videos.