主语: his students, 谓语 start, 宾语 an exciting voyage, 宾补: into an unknown world invisible to the eye（a voyage into somewhere 是一个固定搭配）, 其中 invisibble to the eye是unknown world 的后置定语.
一个英语句子结构的分析----高手进
主语: his students, 谓语 start, 宾语 an exciting voyage, 宾补: into an unknown world invisible to the eye（a voyage into somewhere 是一个固定搭配）, 其中 invisibble to the eye是unknown world 的后置定语.