[求助] Prep-75 (看过讨论帖的解释，但是仍然有疑问)

75.  A recent poll indicates that many people in the United States hold a combination of conservative and liberal political views; i.e., they denounce big government, saying government is doing too much and has become too powerful, while at the same time supporting many specific government programs for health car, education, and environment.

A. they denounce big government, saying government is doing too much and has become too powerful, while at the same time supporting

B. they denounce big government—they say that government is doing too much and has become too powerful—but supporting at the same time

C. they denounce big government, they say that government is doing too much and it has become too powerful, while they support at the same time

D. while they denounce big government, saying that government is doing too much and has become too powerful, at the same time supporting

E. while they are denouncing big government—they say that government is doing too much and it has become too powerful—supporting at the same time

求助： 个人觉得A选项中denounce与support应该是平行结构，但为何后者用ing形式呢？即便按照讨论贴中二楼的解释主语一致时可以省略的话，那也应该是while at the same time support 吧？请NN赐教，谢谢！

参考http://forum.chasedream.com/dispbbs.asp?BoardID=23&replyID=2072539&id=221920&skin=0二楼的解释（while起的是链接作用，如果主句和从句主语一样时候，可以省略从句主语。for example: She kept cooking while talking to her friends.）

denounce 与support 是平行的关系, saying 后面的是插入语. 但是while 有一种用法: while + 动词+ing , 使现在分词短语与主句的动作形成了强烈的对比关系. 意思为: 同时....却   , 强调的是这两个动作同时发生.

见LZM 书137页

sorry,我没有LZM 书，不过while doing sth的结构的是了解的，再请教下是不是while和whereas一样，对平行结构的要求不那么严格亚？谢谢