在美洲大陆上，外来物种是在第一次接触欧洲后引进的。

Across the American continents, exotic species are those introduced after the first European contact.

youdao

这是我有生以来第一次接触野生动物。

It was the first time in my life I had touched a wild animal.

youdao

这个实验是她第一次接触金属丝，让人印象深刻。

This experiment was the first time she'd been presented with wire, which makes it very impressive.

youdao

You would first get exposed in children-- in childhood and then at a point when you're susceptible to the disease.

在儿童期这个较容易受病毒感染时期,第一次接触该病毒,就会引起发病

耶鲁公开课 - 生物医学工程探索课程节选

So I'm going to ask you to come at the New Testament,though, from the outside. If you feel like you know something about it, put those aside for the moment, because when we do the class we'll be trying to get you to see this document as if for the first time, to see early Christianity completely as if for the first time.

所以我要求你们客观地研究新约，如果你觉得你对它略知一二，就请先遗忘片刻，因为我希望你们上课阅读文本时,当做与其第一次接触，第一次接触早期基督教。

耶鲁公开课 - 新约课程节选

A typical problem that you may have done in your first pass at Newton's law, someone tells you a force of 36 Newtons is acting on a mass of whatever, 4 kilograms; what's the acceleration?

在你们第一次接触牛顿定律时,可能见过这么一道典型题目,告诉你,一个 36 牛的力,作用在一个物体上,4 千克吧,问加速度是多少

耶鲁公开课 - 基础物理课程节选