He's never seen one.

他从来没见过一个。

youdao

Hain't you ever seen one, Huck?

你没见过吗，哈克？

youdao

While they were wandering down the street, Heidi found out what a barrel-organ was, for she had never seen one.

当他们在街上闲逛的时候，海蒂发现了什么是手风琴，因为她从来没见过。

youdao

They had seen one hundred twenty sunrises and sunsets.

VOA: special.2009.06.24

So we've seen one example of this, this idea of walking through all the integers looking for the square root.

现在计算机速度很快了，我可以把这个数字设的更大点,计算机会去很快的做这个事情。

麻省理工公开课 - 计算机科学及编程导论课程节选

Well, today I haven't seen one yet actually,

嗯，其实今天我还没见到，

比佛利山庄的美食街 - SpeakingMax英语口语达人

Ryan Arter, the president of Kansas-based Mission:Repair, has seen one iPad so far.

FORBES: iPad's Screen Cracking Far Less Than iPhone's So Far

"I have never seen one of these before, other than on television, " Mr. Lopez said.

WSJ: Accused Killer Leaves Prison After 23Years

It was only 7 am but we had already seen one of the biggest surprises in the safari world.

BBC: The rhino wars of central Kenya