Level 4 · Upper Intermediate
Since that's the case: 既然…就
既然 A，就 B
既然 (jìrán) opens with a fact both people already accept, and 就 draws the natural conclusion: 既然你不舒服，就在家休息吧 "since you're not feeling well, just rest at home". It's "since (that's the case)", not "since (a time)".
Don't reach for 因为 here. 因为 introduces NEW information ("because it rained…"); 既然 works with something the listener already knows, and the second half is usually a suggestion or decision with 就…吧.
Examples
既然你不舒服，就在家休息吧。
jì rán nǐ bù shū fu jiù zài jiā xiū xi ba
Since you're not feeling well, just rest at home.
既然大家都来了，我们就开始吧。
既然大家都來了，我們就開始吧。
jì rán dà jiā dōu lái le wǒ men jiù kāi shǐ ba
Since everyone is here, let's get started.
既然你不喜欢这个菜，就别吃了。
既然你不喜歡這個菜，就別吃了。
jì rán nǐ bù xǐ huan zhè ge cài jiù bié chī le
Since you don't like this dish, don't eat it.
既然他已经知道了，你就不用再说了。
既然他已經知道了，你就不用再說了。
jì rán tā yǐ jīng zhī dào le nǐ jiù bù yòng zài shuō le
Since he already knows, you don't need to say it again.
Common mistakes
✗ 因为你来了，就开始吧。
✓ 既然你来了，就开始吧。
When the reason is already known to both speakers, use 既然, not 因为.
Related grammar points
Practice this pattern in graded stories like A Rainy Saturday (Part 1) inside the Literate Chinese app.
