变绿用英语可以说成 "turn green"。
其来源可能源自于物体颜色变化的表现，比如叶子变黄变红变绿等，或者是指某些东西（如灯）颜色变化为绿色。
例句：
The leaves will turn green in the spring. (春天，叶子会变绿)
The traffic pght turned green, and the cars started to move. (交通灯变绿了，汽车开始行驶)
The grass turned green after the rain. (雨后，草变绿了)