The first one that I will mention is actually something you thought maybe you could do with a single integral, but it is useful very often to do it as a double integral.

第一点就是，有些你以为是用一重积分来做的，但却通常是用二重积分来完成的。

youdao

Do you get to see him often?

你能经常见到他吗？

《柯林斯英汉双解大词典》

How often do you go to church ?

你多久去教堂做一次礼拜？

《牛津词典》

"Today,the goal of modern apocalyptic terrorism is often to do as much disruption as possible and kill as many as possible in order to realy shake up the way in which societies operate and governments make decisions and make the pain so high that decisions are reassessed."

VOA: standard.2010.03.30

I've got to say, we've got to do this more often Right. Let me, let me get to the point.

我必须说，咱们得经常这么干,好，让我，让我说重点吧。

麻省理工公开课 - 计算机科学及编程导论课程节选

But to do that is I recognize not without dangers often severe dangers of its own.

但一旦这么做，我要坦言，不是没有风险,通常还会是来自其本身的巨大风险。

耶鲁公开课 - 政治哲学导论课程节选

He said it was often to do with a culture clash.

BBC: Jersey senator says discrimination claims 'a wake up call'

How often to do we use this technique?

BBC: NEWS | Programmes | More Or Less | The truth behind statistics

Just 14.8% of German children but 45.4% of Turks end up in Hauptschulen, which ought to prepare them for simple trades but often fail to do even that.

ECONOMIST: Germany's Turkish minority