The general rule is that we use made of when the material has not been radically changed or processed, only shaped, and it is still apparent. We use made from when the material has been changed or processed so that it is not apparent. Thus we say:
However, in real life, this general rule (and most rules of grammar and usage) are not carved in stone. Native speakers sometimes do say made from when the material is apparent, and this is reflected in the reading passage you note. (For more examples, search for the phrase “made from” in Google Books.) If you look through the Q&A on this website, you will find that the reading passages often “break the rules” because they reflect real usage. Students should still learn the rules for production and understanding, but they should also be able to understand a reading passage when a rule has been “broken.”
We usually say made of when the original material is shaped or processed in a way that makes it still visible.
Clothes are made of cotton or wool, furniture is made of wood. Meringue is made of beaten egg whites.
When the original material is processed in a way that makes it less obvious, we usually use made from.
Paper is made from wood. Viscose is made from cellulose. Cake is made from flour and sugar and eggs.
Sometimes we say made with when we are talking about one or more components of something.
This bread is made with whole-wheat flour.
These are general rules and you should follow them in tests. You might sometimes see or hear people use made from when you would expect made of, or vice versa. That's why I say this is how we usually express these ideas.
The general rule is that we use made of when the material has not been radically changed or processed, only shaped, and it is still apparent. We use made from when the material has been changed or processed so that it is not apparent. Thus we say:
ردحذفA table is made of wood.
Paper is made from wood.
However, in real life, this general rule (and most rules of grammar and usage) are not carved in stone. Native speakers sometimes do say made from when the material is apparent, and this is reflected in the reading passage you note. (For more examples, search for the phrase “made from” in Google Books.)
ردحذفIf you look through the Q&A on this website, you will find that the reading passages often “break the rules” because they reflect real usage. Students should still learn the rules for production and understanding, but they should also be able to understand a reading passage when a rule has been “broken.”
We usually say made of when the original material is shaped or processed in a way that makes it still visible.
ردحذفClothes are made of cotton or wool, furniture is made of wood.
Meringue is made of beaten egg whites.
When the original material is processed in a way that makes it less obvious, we usually use made from.
Paper is made from wood.
Viscose is made from cellulose.
Cake is made from flour and sugar and eggs.
Sometimes we say made with when we are talking about one or more components of something.
This bread is made with whole-wheat flour.
These are general rules and you should follow them in tests. You might sometimes see or hear people use made from when you would expect made of, or vice versa. That's why I say this is how we usually express these ideas.