spend/pay 只能人做主语sb. spend time/money on sth/in doing sth.sb. pay money for sth. to sb.cost只能物做主语多用来表示钱也可表时间,精力sth. cost sb. money
spend money on sth. spend money in doing sth. sth. cost money pay money for pay for bill
spend money on sth.sth. cost moneypay money for sth.