Originally, Keeling measured the speed of light in the air samples with a laser beam.
起初，吉林用激光束测量光在这些空气样本中的传播速度。
2
The team "combed" breath samples from volunteers with the light pulses.
“梳理”小组通过光脉冲对一些志愿者的呼吸样本进行测试。
3
In a study at Oregon State University, consumers were shown three samples of iceberg lettuce, two of them with varying degrees of light brown on the edges and at the base.