book是什麼意思

book：作名詞指書, 書籍, 卷, 篇, 帳簿, 名冊, 工作簿；作動詞指登記, 預訂, 控告。

例句：

1、This is my book.

2、The book is so difficult that I can not understand.

3、Could you tell me what is the middle idea of the book?