Prep 7

7.  Each year companies in the United State could save as much as $58 billion annually by preventing illness among employees and gain as much as $200 billion through improving performance of workers if they simply provided offices with cleaner air.

 A.　annually by preventing illness among employees and gain as much as $200 billion through improving performance of workers if they simply provided

B.　annually if they prevented employee illness and gain as much as $200 billion through worker performance improved by simply providing

C.  annually in employee illness prevention and gain as much as $200 billion through worker performance improved by simply providing

D. in employee illness prevention and gain as much as $200 billion through improving performance of workers if they simply provided

E. by preventing illness among employees and gain as much as $200 billion through improved worker performance if they simply provided

答案选E。但大家觉得E中这两块对称吗 ?

    我觉得E选项中，by后边是动宾结构，而through后边是名词短语，显然并非最佳答案。可能指示比较下来较好的答案。如果改成by preventing illness among employees and gain as much as $200 billion through improving performance of workers if they simply provided 应该就更好了。大家同意吗 ？

同意阿

这个问题不会存在阿，之前的除了employees是复数就是companies是复数了，前者很明显不适中心词，代词怎么会睬他？  所以就是指代后者阿

E还有两个好处，1.动词形式优于抽象名词    2.-ed分词优于-ing分词

jzq说得对，但我想：代词是老生常谈了，如果可以不用代词就尽量不用代词，这样可以避免歧义，特别是本句有两个复数名词，而且根据规则：从句以代词作主语优先指代主句主语，从而造成歧义。

与此同时，jzq所指：2.-ed分词优于-ing分词  并不是绝对，需要具体情况具体分析，状态的确优于动作，这是大多数情况，但主被动的表达差异、分词伴随或定语修饰的区别，平行和并列等等情况，都去要具体分析从而得出答案。

when i first did the question i chose D, but the answer is E. i was thinking is the word "if they simply provided"  imply that the thing provided is something done. therefore, we should use the "improved performance" rather than "improving performance"?

improved performance is something that workers can provide..

personal opinon..

My opinion： 答案D中they和employees离的太近，有歧义的嫌疑。GMAC认为，形式上的绝对平行显的有些死板，所以会有类似答案E这样的形式，显得句法多变、优美。

阿弥陀佛，还得多多领悟。