1.
In/Under these circumstances...
情况既然这样...
2.
Well, now that you're here,
嗯，既然你回来了，
3.
In that case, I'll ask no more questions.
既然这样，我就不再问了。
4.
Well, if you insist.
好吧，既然您坚持这样。
5.
Well, sir, @ answered the shopkeeper.
“既然这样，先生，”店主回答，
6.
Though now that you've come perhaps you'd like to take a seat."
既然来了，请坐一坐
7.
Since the Communists are "bandits", then the "bandits" should be "suppressed".
既然是“匪”，就应当“剿匪”。
8.
Now that a decision has been taken, let's do it respectively.
既然决定了，就分头去办。
9.
If you make a promise, you should carry it out.
既然许愿就要还愿。
10.
Now (that) you have come, you may as well stay.
你既然来了,不妨就住下。
11.
Well, in that case, let's keep in touch.
好吧，既然如此，保持联络。
12.
Now ( that ) you are here you' d better stay.
你既然来了，（最好）就呆着（或住下）吧。（既来之，则安之。）
13.
As I am in for it, I must proceed.
既然势成骑虎，我就一不做二不休。
14.
If that is so, give me your ring.
“既然这样，就请把那枚戒指送给我吧
15.
Such being the case, how can we change our policy towards Hong Kong?
既然这样，怎么会改变对香港的政策呢？
16.
"Now that you treat me so, I will see."
“既然你这样待我，我就一定要看
17.
Since he insists, I'll let him have his own way.
既然他坚持这样，我就由着他罢。
18.
Since the sea covers the greater part of the earth's surface,
既然海洋覆盖着地球的大部分表面，