七、平行结构
改错题考的最多的一个方向便是平行结构(一) 对等连接词
一共有三类连接平行结构的词
单一式： and, or ,but
相关式： both…and, not … but,
either …or, neither…nor
the same…as；as…as, not so…as, not as…as
such …as, so …that.. too…to, from…to, from…until, between…and,
not only…but also(also可以省略)，Not only +主谓，also
not only…but also(also可以省略)+as well,
短语式： as well as
rather than (而不是)
other than (除…之外)
instead of (代替)
考试的方式往往是搭配中有一个单词是对的，另一个单词却不对
例：John lived in New York since 1960 to 1975,
A B
but he is now living in Detroit.
C D
分析：B错，应改为from。“从某年到某年”要用“from…to…”这个表达法，不能用since …to…。
例：Even as he wrote copiously on so diverse topics
A B
as education ,politics ,and religion ,Lewis Mumford
remained active in city and regional planning.
CD
分析：B错, 改为such diverse topics as, 出现as, 往往要注意前面一半 (二)平行的内容 第一、引导词性的平行，词性的平行本质上是语法作用的平行
例：Photoperiodism is the functional or behavioral response of
A B
an organism to changes in duration of daily, seasonally,
CD
or yearly periods of light and darkness.
分析：D错，应改为seasonal。在daily, seasonally和yearly三个并列的词中，daily和yearly是形容词，seasonally是副词，故改为形容词seasonal,共同修饰名词periods，三个形容词的平行，词性平行 第二、名词单复数的平行
但是如果既有可数名词，又有不可数名词，可以不平行
例：The main advertising media include direct mail,
A BC
radio, television, magazines, and newspaper.
D
分析：D错，应改为newspapers。newspaper为可数名词，在没有任何前置修饰语的情况下一般用复数形式，并且和前面的magazine平行,而mail, radio, television则是不可数名词。
例：The Canadian province of Newfoundland has a rocky coast, a moisture climate,
A B
and probably the best cod-fishing areas in the world.
CD
分析：海岸气候只有一个，但是钓鱼的地方可以有许多个，所以也是不可数名词和名词复数的平行；因此D没有错，A错改为have
第三、时态的平行
例：The poet Marianne Moore was initially associated
with the imagist movement , but later develops
B
her own thyme patterns and verse forms.
CD
分析：B错，应改为developed。句中前半部分谓语为过去时，与之并列的谓语也应用过去时。
例：Because the papaya grows readily from seed , -----
spread from its home in Central America and
now grows throughout the tropics.
(A) to be(B) it
(C) the (D) its
分析：正确答案为（B）。空格前是原因状语从句，后面紧接着是谓语动词，空格处明显缺主句主语。四个选项中只有B能单独作主语。注意spread是过去式，没有数的变化，因为这一动作明显发生在过去时间。spread 和grows为什么时态可以不平行呢？
原来它在Central America 的家乡传播，现在在整个地方传播，now只修饰后面的grow
例：Ducks have been domesticated for many centuries ----
commercially for their meat and eggs.
(A) raised (B) and are raised
(C) raised as(D) are raised
分析：正确答案为B。空格前是一个完整的句子，根据一个空格处如再出现谓语动词一定要有连词这一原则，B为惟一符合条件的选项。故选（B）。 第四、排列位置的平行
例：---the surface of metal, but also weakens it.
(A) Not only does rust corrode
(B) Not only rust corrodes
(C) Rust, which not only corrodes
(D) Rust not only corrodes
分析：正确答案为D。从but also放在动词前可知，not only也须置于动词前，故选D。A、B中的Not only位置放错了，C使句子缺主句，故排除。
对于not only, but also的用法有以下几种：
1、主语+not only +谓语，but also+谓语，正确；例如上面例题中的第四个选项。
2、Not only +主谓，but also+主谓，正确
3、Not only +主语+谓语，but also+谓语，错误 | 
