"to" & "for" ?????

[Abbeycheng]

i dun understand the difference of " to" and " for"?

eg. Learning english is good for us.
eg. The book is readable to us.

Am i correct?

[Delfino]

I don't understand the difference between "to" and " for"?

e.g. Learning English is good for us.

The book can be read by us. / The book is readable by us.

The book can be read to us by our parents for entertainment purposes.

The book is read to us by our teacher for educational purposes.

The book is read by us to gain an understanding of physics.

( An understandig of physics can be gained by reading this book. )

Am I correct?

by is used to express who is doing something (or how something is done)

to and for are used in many different ways
I am not sure how to explain the use of these prepositions.
I think you might need to learn some by heart.