OG-46

lingxia

46. 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.
(A)    associated with other calves, they will require less medication and gain weight quicker than do
(B)    associated with other calves, they require less medication and gain weight quicker than
(C)    associate with other calves, they required less medication and will gain weight quicker than do
(D)    associate with other calves, they have required less medication and will gain weight more quickly than do
(E)    associate with other calves, they require less medication and gain weight more quickly than

正确答案是E，在这里E选项是不是省略了一个do
一般若是句子比较，do都要补出
在省略的时候有没有什么原则可遵循？
谢谢

fair_sword

sure enough, it is omit do