conjunction followed by conjunctive: 既然jì rán…那(么)就 nà(me)jiù . . .
既然你没空,那就改日再谈吧。
Jì rán nǐ méi kōng,nà jiù gǎi rì zài tán ba。
Since you are busy, let’s talk about it some other day.
既然他不愿意,那就算了。
Jì rán tā bú yuàn yì,nà jiù suàn le。
Since he is not willing, let’s leave it at that.
[1] Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.