There are some questions___which have no definite answers.为什么填to?先行词question在从句中当什么成分?

There are some questions___which have no definite answers.为什么填to?
先行词question在从句中当什么成分?

首先questions后面有个定语从句,定语从句的先行词questions在定语从句是不做成分的.
to是个介词,在这里前置了,是answers to the questions,所以用to

the answer to the question，这个固定用法。question做表语，主系表结构。