It takes/took sb. time/money to do

It takes/took sb. time/money to do

It takes/took sb. time/money to do.../做某事花了某人……时间/金钱

it是形式主语，真正的主语是动词不定式to do sth。例如：

It takes her fifteen minutes to walk to the bus stop from her home.

从她家走着到公交车站她需要花15分钟。

It took the old man three days to finish the work.

完成这项工作那个老人花了3天的时间。