it这里是形式主语,真正的主语是to get to London
也就是To get to London takes xx hours.
[用多少时间] 要用动词take
因此这里不能把take换成get,It gets xx hours to get to London.是不正确的用法
其次,你把不定式to get to London 改成介词短语to London 是可以的,句子因此变成
To London takes xx hours.= It takes xx hours to London.
简单来说,take对应的是时间(不能换成get）,get这里对应的是地点 (可以换成reach)
how far is the hill from my home?和
how far is it from the hill to my home?都可以,前者更常用.
前者的主语是The hill.因此回答是 The hill is xx miles from my home.
后者主语是It.回答是It is xx miles from the hill to my house.
it 指代 distance.