当“费用，成本”讲的时候，是可数名词，加-s，作“代价，损失”讲，是不可数名词，不加-s。
expense
读音：英 [ɪkˈspens] 美 [ɪkˈspɛns]
释义：n.费用花费的钱消耗花钱的东西
vt.向…收取费用把…作为开支勾销
第三人称单数： expenses
复数： expenses
现在分词： expensing
过去式： expensed
过去分词： expensed
例句：
1、It was said that he went to great expense to install a lift in the building.
据说他花费巨资在大楼里安装了一台电梯。
2、It was not a fortune but would help to cover household expenses.
这笔钱不算多，但是能帮助支付家庭开支。
expense的可数性
expense的可不可数随意义而改变
expense
[U]不可名词 spending of money etc cost 花费 代价:
an expense of time，energy and cash 时间、 精力、 现金的花费
[C] 可数名词cause of spending 花费的原因:An annual holiday is a big expense.一年一度的假日是一笔大开销. Running a car is a great expense.一辆汽车的经常开支很大.
expenses [pl] money spent in doing a specific job，or for a specific purpose （做某工作或为某目的）花费的钱:
travelling expenses 旅费
House repairs，holidays and other expenses reduced her bank balance to almost nothing.修房，度假和其他开销使她在银行的存款所剩无几.
