平行
1，对平行标志词要敏感，注意未划线部分的平行结构
看到and, but, or, yet就要想到平行，根据语义判断：1>items平行，以及结构平行;2>两个主句平行(完整的主谓结构)有的句子会出现大平行套小平行，要分清楚逻辑层次
2，and、or以及as well as的含义
(1)And连接的items地位平等，这几个item之间并无关联，没有联系。他们的发生或是先后发生，或是各自独立发生。you have a SEQUENCE OF EVENTS, so they should be PARALLEL.
例：
I want to know whether you drink and study(这是我想知道的两件事情)
The sloth hangs from the trees, sleeps 15 hours a day, and moves infrequently enough.(各自没有关系，独立发生)
而The sloth hangs from the trees, sleeping 15 hours a day and moving infrequently enough。就表示了这些动作之间是有关系的!
(2)Or的含义：Stress, alcohol and rich foods identifies the combination of these three factors as a suggested cause of stomach ulcers, whereas stress, alcohol, or rich foods offers three individual possibilities.
(3)as well as的意义：this phrase explains that the essay served as both a critique of previous chemistry and a vision of a new kind of chemistry. (OG解释)
PREP07,p2,90.本句使用了这样一种基本句型：A did one thing, as well as doing another thing.这种句型属于 as well as 的一种使用方法，朗文给出的例句为：The organization gives help and support to people in need,as well as raising money for local charities.
as well as doing something 位于逗号后，对主句的谓语动作做出补充，为正确的习语结构
3，
not only....but also....、but/but also、not....but....的运用
做题的时候要弄清楚句子的意思是递进还是转折,如果是递进not only...but also 没问题,如果是转折的话,就要考虑一下是否是GMAC的陷阱了, but/but also才是表示转折的意思.
Not....but....结构：The structure of this sentence expresses negation and affirmation: Many experts regarded X not as a sign that Y, but as a sign of Z.
(1).在正常语序中: not only … but also.... 应连接两个相对称的并列成分。例如：
Not only Mr Lin but also his son joined the Party two years ago. (连接两个主语)
I not only play tennis but also practise shooting. (连接两个谓语动词)
He plays not only the piano but also the violin. (连接两个宾语)
在正常语序中: 短语本身不可以加入其它成份，比如变成：not only...but it also...是错误的(因为破坏了平衡)。
(2). not only … but also 连接两个主语时，谓语动词要和与其最近的主语保持人称和数的一致。例如：
Not only the students but also the teacher was against the plan. / Not only the teacher but also the students were against the plan.
(3). not only … but also 不能用在否定句中。例如：
误： They don't fear not only hardship but also death.
正： They fear neither hardship nor death.
正： They don't fear either hardship or death.
(4). not only … but also 连接两个分句，并且 not only 位于句首时，第一个分句中的主语和谓语要部分倒装。例如：
Not only does the sun give us light, but also it gives us heat.
这里附上ring_cheng的观点:倒装时可以在短语中插入某类成分，如：not only did sb do sth, but sb also did sth (之所以前后都加入主语，不是为了连接主语，而是为了句子的对仗工整而补足主语，连接的其实是主语的两个不同的谓语动作。又因为not only在句首已经倒装过了，所以but also用正常语序即可。依然满足句子平衡的要求).
not only…but also…的变体总结 -- aeoluseros
1. not only … but also …并不总是这么对称、完整地出现地，以下几种变体也为GMAT所接受：
(1) not only … but …
(2) not only … also…
4，
While在表示转折对比时，有两件events同时发生的含义。While做时间状语也是at the same time(当……时候)修饰主句的动作。
5，
(1) 另外单个neither的用法：
They were not in Shanghai at that time. Neither (nor) were we.
They are not from England. Neither (nor) is she.
(2) run-on sentence的重点在于其改正方法：
1>用一个逗号加上and, but, or或者其他并列连词
2>两个句子中间使用分号
句子完整结构 (结合前面提到的run-on)
1) S+V1+O1 and V2+O2.是很常见的结构. and之后的主语是S, 可是被省了.
2) S+V1+O1, and pronoun(指代S)+V2+O2. 也是很常见的结构.一般在and之后用pronoun指代S作主语是因为and跟S的距离太远.
3) 对于S+V1+O1, and V2+O2.结构，and前并不经常补出逗号，通常and前补出逗号是因为前面是插入语一定需要逗号，或者是为了让句子结构更为清晰，比如前面是定语从句，防止第二个谓语动词V2与定语从句中的动词并列;又比如本题的C选项加了逗号，the yellow jacket’s stinger is comparatively smooth, and can therefore be pulled out and used：used和pulled自己独自成为平行，两者组成的小团体又和前面的is平行，如果都连着写，那么会给读者一个is和used平行的印象(虽然我们并不一定会那么读，但是加了逗号更为清晰了)。
6，also的问题，注意的小点
(1)"X and Y" is normally used to indicate TWO DIFFERENT things. (if you said "the first woman and the first Swedish writer", without the "also", that would normally imply 2 different people)
(2)"X and also Y" is normally used to bestow two descriptions on the SAME person or thing (notice that both of these descriptions are meant to describe Selma Lagerlof).
(3)Also接在both....and....的句型中一定错
