costs doing
spend的主语必须是人,常用于以下结构：
(1) spend time ／money on sth.在……上花费时间(金钱).
例：I spent two hours on this maths problem.这道数学题花了我两个小时.
(2) spend time ／ money (in) doing sth.花费时间(金钱)做某事.
例：They spent two years (in) building this bridge.造这座桥花了他们两年时间.
(3)spend money for sth.花钱买…….
例：His money was spent for books.他的钱用来买书了.