This novel is set in the highly developed city, Shanghai, so once _______ , it will capture the hearts and minds of many ambitious youths.
A. publishes B. having published
C. publishing D. published
解析：选D。句意：这本小说的写作背景是高度发达的城市——上海，所以一旦出版，它将会吸引众多有志青年的关注。novel与publish之间在逻辑上是动宾关系，所以答案只能是过去分词。此处可以认为为了使过去分词的功能更明显地体现，在其前面加上了once；也可以认为是once从句的省略，补全为once it is published。