请教Review分册里语法第38题

tracyxuyang

A study commissioned by the Department of Agriculture showed that if calves exercise and associated with other calves . they will require less medication and gain weight quicker than do those raised in confinement.

为什么是calves 和those 之间的比较，而不是calves require and gain 与 those do 之间的比较

HarrisZheng

比较对象是calves和those raised in confinement. 比较内容是 require less medication and gain weight quicker

如果 calves require and gain 与 those do 之间的比较 请问比什么?

虽说GMAT不需要额外的知识背景, 但是GMAC assumes that参加者都是具有正常思维和智商的.