cost一词在英语中既可以作动词，也可以作名词。
1. 作动词时，意思为“花费”，常用结构为：sth. cost(s) sb. some money.
2. 作名词，意思为：
(1)“价钱，花费”，如 the cost of living 生活成本；
(2) “代价”，如the cost of being famous 成名的代价
Example: It costs a lot to buy a house in this part of London. 在伦敦的这个区买房子会花很多钱。
Example: This ship was built at a cost of 400 million dollars. 造这条船花了四亿美元。
Example: He became famous at the cost of his private life. 他以私生活为代价，获取了成名。
Example: Is it true that the cost of living in Tokyo is the most expensive in the world? 据说东京的生活成本全球最高，是真的吗？
