Yufan, the translation in the book is right. "Est-ce que" is a question mark, as it is "Does" in the english sentence. As in chinese, french has several ways to build questions. Statement: La fille aime le livre (女孩子喜欢这本书) Question: 1) Est-ce que la fille aime le livre? (question mark: est-ce que + ?) 2) La fille aime le livre? (question mark: ?)> In this case, intonation is important, as in oral expression, interrogative intonation would be the only way to know that it is a question. 3) La fille, aime-t-elle le livre? (question mark: inversion >>verb before subject + ?). The use of "-t-" is just for helping in the pronuntiation, it has no grammatical function. "does this book girl like" has no sense.