飞行员必须随时保持警惕。

A pilot must remain vigilant at all times.

《牛津词典》

在一个完全陌生的环境里，你必须随时保持警惕。

You must keep alert when you are in a completely unknown environment.

youdao

驾驶员必须随时对驾驶室内发生的事情保持警惕，把安全放在第一位。

The driver must be on alert for anything that occurs in the cab and make safety his top priority.

youdao

驾驶员必须随时对驾驶室内发生的事情保持警惕，把安全放在第一位。

The driver must be on alert for anything that occurs in the cab and make safety his top priority.

youdao