既然⋯⋯，就⋯⋯
Explanation
表示因果关系，前一分句提出已知事实或前提，后一分句据此得出结论或做出决定。
Expresses cause-and-effect relationship, where the first clause presents a known fact or premise, and the second clause draws a conclusion or makes a decision based on it.
Examples
既然这事你已经决定了，我就不说什么了。
Since you've already decided on this matter, I won't say anything more.
既然外面下雨了，我们就明天再去吧。
Since it's raining outside, let's go again tomorrow.
Related Grammar Points
⋯⋯ ，可见 ⋯⋯HSK 4四56
句子的类型 · 因果复句
这个结构用于从已知的事实或现象中推断出结论，'可见'表示'由此可以看出'或'可以推断出'。
This structure is used to draw a conclusion from known facts or phenomena. '可见' means 'it can be seen from this' or 'one can infer that'.
Examples (2)
他的中文水平很高，可见他在留学期间学习是多么努力。
His Chinese proficiency is very high, which clearly shows how hard he studied during his time abroad.
他在我困难的时候一直帮助我，可见他是我多么好的朋友。
He has always helped me when I was in difficulty, which demonstrates what a good friend he is.