你以前用过这种软件吗？

Have you ever used this software before?

《牛津词典》

你以前用过玉兰油这牌子的产品吗？

Have you ever used Olay products before?

youdao

店员：那您以前用过什么药吗？

Shop assistant: What medicine have you used before?

youdao

And we can calculate that with the formula that we used, which was just n minus l minus 1 equals the number of nodes.

这个我们可以用我们以前用过的那个公式来计算，也就是节点数等于ｎ减去ｌ减去１

麻省理工公开课 - 化学原理课程节选

We can make some substitutions here using some of the derivation on the previous board which will give us the Planck constant divided by 2 pi mass of the electron times the Bohr radius.

在这里我们也可以,用我以前在黑板上写过的一些词来取代它,得到的是普朗克常数除以2π电子质量,再乘以波尔半径。

麻省理工公开课 - 固态化学导论课程节选

Now. You might look at that and say, well that's just a lot like what we had over here Right? We had some additive constant plus a simpler version of the same problem reduced in size by 1.

现在你可能会看着这个说，这很像我们以前做过的,对不对？我们用一些附加的常量,加上问题的另外一个规模缩小了1的,简化版本来代替这个问题本身。

麻省理工公开课 - 计算机科学及编程导论课程节选