Expanding sentences means adding joint elements such as attributes, adverbials and complements according to the needs of expression, so as to make the meaning of sentences or chapters more specific and substantial. So you can describe it before the subject of the sentence "collection of books", such as "exquisite collection of books", "ancient collection of books" and "precious collection of books". You can also add adverbials before the predicate "shelve" to let people know how to shelve, such as "orderly shelve" and "disorderly shelve". If it's not enough, put it on the object's bookshelf. I'll give you an example after synthesis. "Some precious books are usually neatly arranged on that dark brown bookshelf."