You can be alert, even though the intensity of the stimulus is quite low.

即使刺激的强度很低，你也要保持警惕。

We must be alert to the possibility of danger.

我们必须认识到危险的可能性。

It's a very intense job, and they have to be alert every moment.

这是高度集中的工作，他们需要时刻保持警惕。

We must be alert to these signals and respond with the compassion and care that are hallmark traits of what it means to be a woman, anywhere, everywhere.

我们必须警惕这些信号，以同情和关爱来回应，这些信号是标志性特征，说明在任何地方、在所有地方做女人意味着什么。

Be alert when driving.

驾驶时保持警觉。