This was a simple sign error, because it's cheaper to save fuel than to buy fuel, as is well known to companies that do it all the time -- for example, Dupont, SD micro electronics.
这是一个简单的符号误差 原因就在于，省油比买油要便宜， 众所周知，很多企业也都一直这样做。 比如，杜邦，SD微电子。