OG verbal分册第38题~关于比较中助动词省略问题

monsterjane

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

og上说do must be omitted from the comparison.并且还说, the verb do ungrammatically interrupts the comparison and should be eliminated.

我想问下问下为什么呢~~~？是因为与will表将来时不平行吗？？

yeye523

我觉得如果是E选项的话，加上do和去掉do都可以，原因在于前面是require，一般现在时，do作为与之平行的助动词也一样；
而ABD的do都分别和前面的will require, required, 和have required不平行，破坏了平行结构。

echomaotw

搂住可以post OG原话吗？下面是其他论坛老外的解释

as far as the "if X happens then Y happens" construction:

this is a little different, because the "if" and "then" parts are SIMULTANEOUS in this context.

in other words, "the calves exercise and associate" is an ONGOING thing. also, "they require less medication" is an ONGOING thing.
since both of these things are taking place at the same time, it would be illogical to place them in different tenses.