1、cost用作动词表示某物值多少钱或者说“得付多少钱去购买”,主语一般是表示所买的东西的名词.cost是不规则动词：cost, cost, cost
例：
My father bought a new car.It cost him ￥60,000.
我父亲买了辆车,花了他6万元.
How much does this watch cost?
It cost sixty yuan.
这块手表多少钱?60元.
2、Sb.+spends+钱/时间+on sth./(in) doing sth.
例：
I spent 80 yuan on the dictionary.
这本字典我花了80元.
I spent 2 hours on my homework yesterday.
比较：I spent 2 hours (in) doing my homework yesterday.
我昨天花了两个小时做作业.