98。Hotco oil burners,designed to be used in asphalt plants, are so efficient that Hotco will sell one to the Clifton Asphalt plant for no payment other than the cost savings between the total amount the asphalt plant actually paid for oil using its former burner during the last two years and the total amount it will pay for oil using the Hotco burner during the next two years. On installation, the plant will make an estimated payment, which will be adjusted after two years to equal the actual cost savings.                Which of the following, it it occurred, would constitute a disadvantage for Hotco of the plan described above?        

(A) Another manufacturer's introduction to the market of a similarly efficient burner

(B) The Clifton Asphalt plant's need for more than one new burner

(C) Very poor efficiency in the Clifton Asphalt plant's old burner

(D) A decrease in the demand for asphalt

(E) A steady increase  in the price of oil beginning soon after the new burner is installed

答案是E，虽然选对了，但是还是不明白这个design究竟efficient在什么地方？也就是飘红的部分不理解。还有就是在安装后，为什么就可以adjusted to equal  the actual cost savings after two years了呢?不明白的实在太多了，请nn指教。

晕，刚才一急，还发到语法版去了……

Hotco oil burners,designed to be used in asphalt plants, are so efficient that Hotco will sell one to the Clifton Asphalt plant for no payment other than the cost savings between the total amount the asphalt plant actually paid for oil using its former burner during the last two years and the total amount it will pay for oil using the Hotco burner during the next two years.

H的油炉，是设计给沥青厂使用的，非常的高效，以至于呢H准备卖一个给C的沥青厂。而且呢，不要付钱。

只是把节约的成本当成购买的费用付给H就可以了。

什么样的成本才叫节约的成本呢。给了个定义：【在过去两年里使用老的油炉时候沥青厂为油所付的钱】和【在未来两年使用H油炉的时候将为油所付的成本】的差值。

如果油炉的效率提高的话，老油炉应该耗油，H油炉应该省油。H工厂就要这油钱上节约的下来的成本，来当作购买H油炉的费用。

谢谢楼主！！