我不是在开玩笑，弗兰克。那边有一头奶牛，就在那里站着呢。

I'm not kidding, Frank. There's a cow out there, just standing around.

《柯林斯英汉双解大词典》

一头奶牛站在铁轨上。

A cow stood on the tracks.

《柯林斯英汉双解大词典》

一头奶牛讨厌和其他牛交朋友。

A cow hates making friends with other cows.

youdao

So, it's awkward to have to wait for a cow to get infected before you can vaccinate a population.

在给人们预防接种之前,你只有干等着,直到有一头奶牛感染了病毒才行

耶鲁公开课 - 生物医学工程探索课程节选

One is that you got to get the vaccine from cows, so you got to have an infected cow in order to produce the vaccine.

一是,你若要想从奶牛身上得到疫苗,那就得有一头奶牛感染病毒

耶鲁公开课 - 生物医学工程探索课程节选