我们一般会说... ooo....so that's how it is... 问题是英文没有固定的这个说法, 要看情况才知道用什么好. oh, I see有时候也可以 oh, really? 也可以 真的要看情况. 还有, 不能说 "how to say in English?" ...how to 这两个字不要放在一起, 应该说"how do you say ... in English?" 后者 "how can I say ... in English?"

there is no good direct translation. but if you're in a situation in which someone says or does something strange, but then explains it in way that makes it no longer seem strange, you can say "no wonder!" or "that explains it!" It's similar to 原来如此 I think.