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
 
1.修饰-- 副词修饰形容词（一级排除A,B,C）
the adverbial phrase more quickly than to modify the verb phrase gain weight.
In A, B, and C, quicker than is incorrect because an adjective should not be used to modify a verb phrase(考试的时候能迅速找出选项差异才能分辨出这个3-2split, 较隐含的3-2split).
 
2.平行结构（一级排除A,B,C,D） 
   时态一致
表事实宾语从句可以用一般现在时，本题主要是时态要一致。

3. 比较结构
A． 主语的比较 此处 省略了后面的谓宾结构  ????
B． 比较词的选择  v。+ more + adv. + than ;  adv. 修饰 V. 合理

对主系表的句型主语比较：
A is/has + adj. than B …. AB为对等名词, 此时 不用补出 系动词。

对主谓宾全的句型主语比较：
A do sth than B do.（AB为对等名词，加do是为了显示这是一个可以发出动作的名词，因而确定是主语，进而确定是主语对比）