The walls are made from old glass bottles that are glued together.

问题描述:

The walls are made from old glass bottles that are glued together.
The roof is made from discarded tiles.为什么用be made from,怎么不用be made of.be made of不是能看出原材料的那种吗?

to be made of可看成是一种含‘物理变化’的制作,即保存原质只是形状变化的制作;
to be made from则可看成是一种包含‘化学变化’的制作,即有某种质变的制作.