科学家在实验中使用了一道激光束。

The scientist used a laser ___beam in the experiment.

正当我开始感到相当不耐烦时，一扇门打开了，让一道光线射入了黑暗的房间。

I was beginning to feel rather impatient when a door opened, letting a ___beam of light come into the dark room.

汽车的前灯发出一道强光，穿透了浓雾。

The car's headlights sent a powerful ___beam through the thick fog.