第一单元是本册的开篇曲。的翻译：The first element is the opening song of notebooks. 什么意思？中文翻译英文，英文翻译中文，怎么说？

青云英语翻译

The first unit is the opening song of this book.

The first element is the opening song of notebooks.

The first unit is this book introduction tune.

This book is the first module of the song.

The first element is the opening song of notebooks.