「既然」

前提摆在那儿了，那就……。

既然来了，就坐吧。       Since you're here, take a seat.
既然不想说，就算了。     If you don't want to talk, fine.

既然 = 既定的前提 → since / seeing that / now that

三档

中文	英文	语气
既然（日常）	since	最常用
既然现在	now that	强调新状态
既然（正式）	seeing (that)	书面

since 的坑

since 有两个意思：

自从……以来         →  完成时搭配      I've been here since 9.
既然……              →  一般时搭配      Since you're here, …

看后面的时态就知道它是哪一种。

动手

既然都来了，多待会儿。

✅ Since you're here, stay a while.

既然你这么说……

✅ If you say so. / Since you put it that way.

既然决定了，就别后悔。

✅ Now that you've decided, no regrets.

既然下雨，就别去了。

✅ Since it's raining, let's skip it.

小卡片

既然（日常）    →  since
既然（现在）    →  now that
既然 + 如此     →  if + so / in that case

——下一课：「总之」。