cost [kɔst]
n.
1.价钱,价格；代价；费用；成本2.牺牲,损失3.支出,花费,开支4.[用复数]【法律】诉讼费(尤指判处败方偿付胜方的诉讼费用)
vt.
1.花费；价格为；值：例句:It must cost a good deal to live here.
住在这里一定要花很多钱的.2.使付出；使损失,使失去：例句:Careless driving cost him his life.
开车不小心使他丧了命.3.需(努力)；费(事)：例句:Courtesy costs little and means much.
礼貌不费事,意义却很大.4.costed,costing 估计…的成本：例句:The work was costed by the engineer at $50,000.
这项工程据工程师估价为50 000美元.
vi.
1.估计成本：例句:We want a man who must be able to cost.
我们需要一个能计算成本的人.2.需要花费,需要付出高昂代价：例句:The furniture in the living room really costs.
起居室里的这套家具真花了不少钱.
短语
1.at all costs不惜任何代价,无论如何2.at any cost=at all costs3.at cost按原价,照成本4.at the cost of以…为代价5.cost someone dear (或 dearly)使某人付出沉重代价,使某人大受损失6.cost what it may不惜任何代价,无论如何7.count the cost(做事前)权衡利害得失；估计不利条件8.to one's cost吃了苦头之后才…,由于付了代价才…
变形:
vt.cost或costedcosting
以上来源于:《21世纪大英汉词典》
如果it指代某样东西,比如a book,这时It costs 5 yuan.是可以的.
如果it是形式主语,用cost不行的