过去式是was/were  good at，中文意思是擅长于

例如

The strangers were good at judging if the person they were looking at was tired， and， if they were sleepy， their attractiveness score was low.这些陌生人善于判断他们所注视的人是否疲倦，而如果他们昏昏欲睡，他们的吸引力得分就会很低。