By happy coincidence, Robert met Richard and Julia and discovered they were experiencing similar problems.幸运的是，罗伯特碰巧遇到了理查德和朱莉娅，发现原来他们也碰到了类似的问题。The economy is experiencing an upturn.经济正在好转。Many poor households are experie...
无差异曲线通常呈凸形.An indifference curve is usually assumed to be convex.我们现在开始接触到值得引起注意的无差异曲线.We come now to the really remarkable thing about indifference curves.而既往吸烟者同不吸烟者之间无差异.Similar calculations erased the sick - day gap ...