The first action explains the means (the instrument or vehicle) by which the second action is carried out:
Zhōng guó rén yòng kuài zǐ chī fàn
Chinese people eat with chopsticks. (instrument)
(The first action, 用筷子yòng kuài zǐ ‘using chopsticks’, indicates the instrument with which the second action, 吃饭 chī fàn ‘eat’, is carried out.)
Tā zuò huǒ chē shàng bān 。
He goes to work by train. (vehicle)
(The first action, 坐火车zuò huǒ chē ‘by train’ (lit. sit on train), indicates the means by which the second action, 上班 shàng bān ‘go to work’, takes place.)
 Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.