cost 什么时候用作复数请举例说明一下.

很少用复数，可能时表示很多笔费用的时候。比如，He pay a lot of costs for the girl.
cost: [ kɔst ]
n. 代价,价值,费用
v. 花费,值,需要
[计算机] 费用

词形变化:
形容词:costless 名词:cost-lessness 动词过去式:cost 过去分词:cost 现在分词:costing 第三人称单数:costs

例句与用法:
1. He saved his daughter from the fire but at the cost of his own life.
他牺牲了生命，把女儿从大火中救出来。

2. Your crime will cost you your life.
你的罪行将使你失去生命。

3. Her irresponsible behaviour cost her father many sleepless nights.
她那不负责任的行为使她父亲许多夜不得安眠。

4. Dangerous driving could cost you your life.
开车不注意安全有生命危险。

5. That mistake cost him dear: he lost the game because of it.
那个差错使他付出了沉重的代价: 他因而输了这一局.

6. Has this project been costed?
这项工程估价了吗?

7. How much/What does it cost?
这东西值多少钱?

8. These chairs cost 40 each.
这些椅子每把价钱为40英镑.

作“成本”讲时用复数
如：to cut down costs 降低成本
We have had to raise our prices because of rising costs.
因为成本日益上涨，我们不得不提高价格。

当用与损失的时候.
IT WILL BRING GREAT COSTS IF YOU CONTINUED DOING THIS.
如果你再继续下去的话,它会带来很到的损失