But traditional guidelines say not to use tPA if more than three hours have passed after the first signs of a stroke.

VOA: special.2009.08.12

There are some important signs, I think, especially in the first two books of Paradise Lost of what we can think of as Milton's - it's a literary fantasy, a literary fantasy of forgetfulness.

我认为有一些重要的迹象，尤其是在,《失乐园》的前两册书中,从那里我们可以思考弥尔顿之所想,这是一次对于遗忘的文学幻想。

耶鲁公开课 - 弥尔顿课程节选

Breathing in two hundred parts per million of carbon monoxide will cause the first signs of poisoning.

VOA: special.2011.01.25

First,immediately leave the area if you recognize the signs of carbon monoxide poisoning in yourself or others.

VOA: special.2010.02.02

Arick first showed signs of the disease when he was about two years old.

VOA: special.2009.07.28

The first trap shows no signs of oil, only mud stirred up by recent storms.

VOA: standard.2010.05.06

"One of the things we found consistently in the academic literature and elsewhere was that the first responders, state and local law enforcement, did not recognize the signs of human trafficking."

VOA: standard.2010.07.23