逗号的问题

216. Many policy experts say that shifting a portion of health-benefit costs back to the workers helps to control the employer's costs, but also helps to limit medical spending by making patients more careful consumers.

(A)  helps to control the employer's costs, but also helps

(B)  helps the control of the employer's costs, and also

(C)  not only helps to control the employer's costs, but also helps

248. By offering lower prices and a menu of personal communications options, such as caller identifica­tion and voice mail, the new telecommunications company has not only captured customers from other phone companies but also forced them to offer competitive prices.

(A)  has not only captured customers from other phone companies but also forced them

(B)  has not only captured customers from other phone companies, but it also forced them

(C)  has not only captured customers from other phone companies but also forced these companies

but also 之前有没有逗号对句子的表达来说有什么区别吗？

在我看来 the same，加逗号因为句子很长，停顿一下，方便读者看懂

248我觉得该选c啊

73. (28457-!-item-!-188;#058&003634)
Evolutionary psychology holds that the human mind is not a "blank slate," but instead that it
comprises specialized mental mechanisms that were developed as a way of solving specific
problems human ancestors faced millions of years ago.
(A) the human mind is not a "blank slate," but instead that it comprises specialized mental
mechanisms that were developed as a way of solving
(B) the human mind is not a "blank slate" but instead comprises specialized mental mechanisms
that were developed to solve
(C) the human mind, instead of a "blank slate," it comprises specialized mental mechanisms that
have been developed to solve
(D) rather than it being a "blank slate," the human mind comprises specialized mental mechanisms
that have been developed as a way of solving
(E) rather than the human mind's being a "blank slate," that it comprises specialized mental
mechanisms that were developed as a way of solving

不好意思lz，借这个帖子贴一道prep题，本题选B。但是用的是not...but instead...请问这个表达可以么？还有一个问题。B中的not与but之后的内容不平行啊！一个是名词，一个是句子。谢谢了！

(B) the human mind is not a "blank slate" but instead comprises specialized mental mechanisms
that were developed to solve

not...but instead应该等同于not...but rather的用法吧

B说不出这样用的理由，只是感觉读起来没太大问题，而且其它选项错误明显

我查了but instead的用法，相当灵活。请看例句：

to nemo11: 逗号好像没影响，这个结构中我没有遇到要区别逗号的。注意not only, but also的对称就可以了吧.

to goyce36: 似乎你这题还是考not, but结构吧, 有but instead这个固定搭配么？这个题目B看起来是不咋对称，不过也只有它比较好点.