The safe-light should be fixed four feet above the table.

安全光应该固定在桌上四英尺处。

Do the following to ensure the safe operation of your smoke detector: if your smoke detector is working properly, the red light should be on.

为确保您的烟雾探测器的安全运行，请执行以下操作：如果烟雾探测器正常工作，则红灯常亮。

I was afraid that the small, light, safe world of notes and cassettes was too artificial and too vulnerable to withstand actual closeness.

我担心那小小的、轻轻的便条和磁带的安全的世界太过造作，太过脆弱，以致于没法经得起近在咫尺的考验。

A laser beam like the one pictured up top combines short and long pulses of light to identify individual molecules with a high degree of precision from a safe distance.

一道激光射线由或短或长的光脉冲组合而成，从而能在一个安全的距离高精度地辨别单个的分子。