首先，阳光照射不到那么深的地方，所以它完全是黑暗的。

First of all, sunlight doesn't reach that far down so it's totally dark.

youdao

“很好，”士兵说，“那么，首先你要帮我从这口井里出来。”

"Good," said the soldier, "then in the first place help me out of this well."

youdao

首先，他们解释说，如果一个给定的变量在影响幸福感方面发挥了作用，那么我们应该预期该变量的任何变化都与所观察到的幸福感变化相关。

First, they explain that if a given variable is playing a role in affecting wellbeing then we should expect any change in that variable to correlate with the observed changes in wellbeing.

youdao

So, how do we figure out first how to draw the skeletal structure of this molecule here?

那么，我们如何来解决它,首先是如何画出这个分子的骨架结构？

麻省理工公开课 - 化学原理课程节选

And so the first thing we're going to spend a fair bit of time on is trying to get clear on what's a person?

那么首先我们,需要花一点时间,搞清楚人是什么

耶鲁公开课 - 死亡课程节选

What is the present value of that? Well, the first-- each payment we'll call a coupon-- so it pays one pound one year from now.

那么它的现值又是多少呢,首先,每一次支付的数额称为一个券息,从现在开始每一年都要支付一英镑

耶鲁公开课 - 金融市场课程节选