求教大全的一道比较题，对答案报有疑问
32.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
the key:E
gemj:这个句子之所以不补出，而且THAN的前面虽然有宾语，但是双重动宾结构。从语法上、逻辑上都不会产生those raised in confinement与weight或medication相比较的嫌疑。当然，就这个例子来说，如果补出，并不算多余。这才是补与不补均可的情况吧。
既然补出，并不算多余,那为什么A不对?A似乎更idiomatic and grammatically,因为if引导的条件从句用一般现在时主句不是应该用将来
谢谢大侠们了 | 
