"Cost" 的 past tense 一定是 "cost" 嗎？

動詞 "cost" 的過去式 (past tense) 和過去分詞 (past participle) 一定是 "cost" 嗎？

答案是：不一定。"Cost" 的 past tense 和 past participle 可以是 "cost"，也可以是 "costed"，取決於 "cost" 本身的定義。

當 "cost" 解作「花費」或「喪失」時，它的 past tense 和 past participle 都是我們熟識的 "cost"：

My trip to Europe has cost me a fortune. (去歐洲的旅程花了我很多錢。) 

Driving under the influence of alcohol cost him his life. (醉酒駕駛使他喪命。)

但當 "cost" 解作「估價」時，它的 past tense 和 past participle 則是 "costed"：

The proposals have been costed at five million dollars. (提案所涉及的費用被估價為五百萬元。) 

We have costed out our project carefully. (我們已小心地估算了工程的成本。)