为什么树叶不能只是改变颜色，继续在树上生长，而当春天到来的时候再变回绿色？

Why can't leaves change colors, stay on their trees, and change back to green again when spring comes?

youdao

为什么树叶不能只是改变颜色，继续在树上生长，而当春天到来的时候再变回绿色？

Why can't leaves change colors, stay on their trees, and change back to green again when spring comes?

youdao