选c.(1)spend的主语通常是人,往往用于以下句型：
（sb）spend some money/some time on sth.
(sb)spend some money/some time(in)doing sth.例如：
I spent fifty yuan on the coat.
= I spent fifty yuan (in) buying the coat.我花50元买了这件大衣.
He spent three days on the work.
= He spend three days (in) doing the work.我干这项工作用了3天.
(2)take常用于“占用、花费”时间,其主语通常为形式主语“it”或物.句式是：
It takes/took sb.some time to do sth＝Sth.takes sb.some time.例如：
It took me three years to draw the beautiful horses.
画这些漂亮的马花费了我3年时间.
The work will take me two days.这项工作花了2天时间.
(3) pay为“付款、赔偿”之意,主语通常是人,往往是sb.pays some money for sth或pay sb.(some money for sth) 例如：
I paid fifty yuan for the coat.我花50元买了这件大衣.
He has paid the doctor 50 pounds for the medicine?他买药已付医生50英镑.
How much did you pay him?你付他多少钱?
(4) cost的主语必须是某物.spend … on sth．/in doing sth．的主语必须是人.pay … for 的主语也是人.It takes + sb．+ 时间（或钱）to do sth．的主语则必须是形式主语It.动词cost的常用用法是sth.cost (sb.) some money.