1. 含义：

两个或两个以上句法、功能相同的词，词组或句子，通过并列连词、并列词组连接起来而构成，共同承担句子的某一成分的结构叫做平行结构。

2.类型：

(1) 比较平行

1) A than B

2) (not) as A as B

3) (not) so A as B

4) (not) such much as A as B

3. 用法

(1)比较对象前后的形式和功能完全一致。

例如1

It is far easier to ride a bicycle than to explain in words exactly how a bicycle is ridden.

解析：than之前是to ride，根据前后一致的原则，than后面应该也是to do的形式，所以用to explain。

(2)对于前面出现的不可数名词或单数名词，用that代替;可数名词用those代替。

例如1

The title of this book is more interesting than that of that book.

解析：比较的是这本书与那本书的title，是单数名词，所以用that代替。

例如 2

The contents of this book are more interesting than those of that book.

解析：比较的这本书与那本书的contents，是复数名词，所以用those代替。

题目检测

题目检测 1

At that time, chopsticks—which were then called “Zhu”— were used for cooking rather than to eat.

A. NO CHANGE

B. The purpose of eating

C. when one ate

D. eating

解析：通过题中的than看出是比较平行的考点，根据“比较对象形式和功能完全一致”的原则，than前面是cooking，所以than后面需要是动名词的形式，A的to eat、B的the purpose和C项when从句都与之前不一致，所以排除A、B和C项，所以选D。

题目检测 2

It was said that Mary could classify three group of ants a minute and, using a magnifying glass, could classify group of ants down to the 9th magnitude-sixteen times fainter than humans.

A. NO CHANGE

B. the human eye.

C. that of the human eye

D. what can be seen by the human eye.

解析：通过题中的than看出是比较平行的考点，题目说玛丽用放大镜识别不同族群的蚂蚁，根据“比较对象形式和功能完全一致”的原则，than前面使用一种方式识别蚂蚁，所以than之后也需要另一种方式，而无论是humans, the human eye还是that of the human eye都不能表达到位，所以排除A/B/C选项，所以选D。

题目检测 3

The equipment of this building, which has been 400 years old, is so much complicated as that building.

A. NO CHANGE

B. as one building.

C. as that of that building.

D. as this building.

解析：通过题中的than看出是比较平行的考点，题目比较的是这个大楼的设备和那个大楼的设备，根据“不可数名词或单数名词，用that代替”的原则，than后面应该用that替换，而A项的that building对应than之前的this building，所以需要另外一个that代替equipment，而无论是that building, one building还是this building都不能表达到位，所以排除A/B/D选项，所以选C。