"With that,I expect the security agencies to be 24-hours alert.

VOA: standard.2009.07.30

Because it's a very intense job they have to be alert every moment.

因为是高度集中的工作,他们需要时刻保持警惕。

普林斯顿公开课 - 国际座谈会课程节选

General Fonseka,in the letter, says Sri Lanka asked India on October 15 to place troops on alert in case they would be needed to intervene to foil a coup on the island.

VOA: standard.2009.11.14

"I hope that what a study like this will do would be to help alert clinicians, residents in training, and medical students that severity is an important factor to consider in planning treatment,".

VOA: standard.2010.01.08

"It's physiological and it's emotional." "Physiologically,we have a tendency when we come into a situation that seems dangerous we get a lot of chemicals flowing through our bodies to help us stay alert, to be able to act if we need to act.

VOA: standard.2010.07.01