be made of 和be made from都是"由……制成"的意思.如果制成的东西还看得出是什么原料做的,就用of,如果已看不出是用什么原料做的,则应用from.be made out of是指从什么东西被改造成另一种东西.
The desk is made of wood.这张桌子是由木头制成的.
This paper is made from wood.这种纸是由树木制成的.