因为书籍是人类进步的阶梯的翻译：Because the book is the ladder of human progress 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

Books are the ladder of human progress

Because the book is the ladder of human progress

Because the books are the steps and ladders which the humanity progresses

Because books are human progress ladder

Because the book is the ladder of human progress