原文 'AN APARTMENT OWNER WOULD PROVIDE AN EXTERNAL BENEFIT IF SHE INSTALLED A SMOKE DETECTOR. bUT SHE DOESNT CONSIDER HER NEIGHBOR'S MARGINAL BENEFIT WHEN SHE IS DECIDING WHETHER TO INSTALL A SMOKE DETECTOR. THERE IS UNDERPRODUCTION'
我不明白为什么 EXTERNAL BENEFIT 就会造成UDERPRODUCTION.
讲一下呗 | 
发表于 2010-5-30 10:35
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