Question

i think you have what you have

I think you have something belongs to me
I think后面you have.应该是宾语从句
在宾语从句里面you have something that belongs to me
that引导的是什么?状语从句还是定语从句?
那是否可以是宾语的补足语？
I fully believe that he will do what he has promised这句是否和上面一样呢？
that后面是宾语从句？
do谓语，what he has promised是修饰do?应该是状语从句？

Answer 1

that引导的是定语从句,从句缺主语,也就是这句话在意义上来说,something就是从句的主语.原句可以拆分成：you have something.Something belongs to me.
I fully believe that he will do what he has promised
这句话that引导的是宾语从句.后面的what引导的也是宾语从句,这是有特殊疑问词引导的宾语从句.也就是说,do这个动词的动作对象是（what he has promised）“他所承诺的事”.
这两句话里边都没有你说的状语从句,看来你对状语从句的理解有误.状语从句
的类型很多,有时间、地点、原因、目的、结果、条件、让步等类型,总之所以的状语从句在整个句子中都是充当状语的.你说的两个句子里都没有状语,更别说状语从句了.