If hoarseness continues or the cause is unknown, doctors should perform an examination called a laryngoscopy.

VOA: special.2009.09.02

- "She lived unknown and few could know"-- how can she be unknown if few know anything about her?

她不为人知地活着，鲜有人知道她“,如果有任何人知道关于她的任何事情,又怎么能说他不为人知呢？

耶鲁公开课 - 文学理论导论课程节选

If you do that, you will find there is one unknown, which is v0, and we can solve for v0.

这样就只剩下一个未知量了,也就是 v0,我们就能解出 v0

耶鲁公开课 - 基础物理课程节选