I happen to know the answer to your question.
问题描述:
I happen to know the answer to your question.
the answer to your question.
to可以换成of 或者 for
还是说,这是一个习惯用法,所以不能换?
答
没错.
的确是习惯用语.
其他的还有比如
the road to
the key to
你是有心人啊