Explanation: Have you ever seen a "star" drifting slowly overhead, but not known what it was?

说明：你有没有经历过这样的情景：看见一颗“星星”慢慢划过天际，你却不知道那是什么？

youdao

Most animals on land are known to us, but many living things underwater are not.

陆地上的大多数动物我们都知道，但水下的许多生物却不为人所知。

youdao

The Clinton Administration says it will lift the ban on their entry but it's not known when.

克林顿政府表示将解除对他们入境的禁令，但尚不清楚何时。

youdao

June Simms has more. Steve Martin is well known for many things, but music is not one of them.

VOA: special.2009.07.17

The time was in the early 70s, so factory farming was not well-known, was not as dominated as it is today, but it still existed.

那时是70年代早期，工厂化养殖并不为很多人所知,也不如今天这样占主导地位，但当时已经出现了这种方式。

普林斯顿公开课 - 人性课程节选

I'll bet even all of you can remember songs that you have known all your life, but not other things.

我打赌你们很容易就能想起你们曾经,听到的歌曲,但别的事就很难

耶鲁公开课 - 古希腊历史简介课程节选

He had a prior record of petty crimes committed when he was under 18 and is known to have been rebellious in his youth, but was not known to French security services, Molins said.

CNN: French police arrest suspect in soldier's stabbing

Friendly, of the federal appeals court in New York, who was legendary for his scholarship and erudition, but was not known as an especially partisan figure.

NEWYORKER: No More Mr. Nice Guy

The singer was popular, but not widely known.

NPR: 'Elvis at 21': Photos of a King in the Making