be good at的過去式

過去式是was/were  good at，中文意思是擅長於

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.這些陌生人善於判斷他們所注視的人是否疲倦，而如果他們昏昏欲睡，他們的吸引力得分就會很低。