当树叶改变了颜色，我们通常用英语表示为“the leaves have changed color”。这个短语的来源可能来自于树叶随着季节的变化而改变颜色的自然现象。例句：
The leaves on the trees have changed color from green to red and yellow.
I love how the leaves change color in the fall.
The changing colors of the leaves are a sign that winter is coming.
中文翻译：
树叶的颜色已经从绿色变成了红色和黄色。
我喜欢秋天树叶改变颜色的样子。
树叶改变颜色是冬天来临的迹象。