It's ( two hour's walk ) from here to my school .注：对括号部分提问

It's ( two hour's walk ) from here to my school .注：对括号部分提问
____ _____ ______ it from here to your school
前两个空为什么填 “how far” 而不是 “ how long”
“how long”难道不能用来提问路程吗?
额..1楼的说一个是长短，一个是距离.那是什么的长短，什么的距离？（时间、路程....等）