SAT文法知识系列栏目说明：每期分享3-5个文法知识点，帮助大家更好地备考SAT。
一、平行结构
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+倒装
3. 用法
(1) 谓语内容一致，比较两个主语，补出谓语动词:do, does, did, is, am, was, were 或are。
例如1
I helped you more than my brother helped you.
解析：than前后的谓语内容都是helped you，所以可以把than后面的helped you变为did。变为下句：
I helped you more than my brother did.
(2) 比较+倒装：
当第二个主语过长，常常把助动词放在第二个主语前。
例如1
The air outside has a higher concentration rate than the air inside the room does.
The air outside has a higher concentration rate than does the air inside the room.
题目检测
题目检测 1
Yesterday Tom went to the cinema, which is located in the east part of the city, earlier than they did.
A. NO CHANGE
B. do
C. was doing
D. were doing
解析：通过题中的than看出是比较平行的考点，根据“谓语内容一致，比较两个主语，补出谓语动词”的原则，比较的对象是went to the cinema这件事，而且是一般过去时，所以补出谓语动词did，A的to eat、B/C/D项do, was doing和were doing形式都错误，所以排除B、C和D项，所以选A。
题目检测 2
Mary, who is a high school student of this town, is currently studying SAT harder than I was.
A. NO CHANGE
B. were
C. are
D. am
解析：通过题中的than看出是比较平行的考点， 根据“谓语内容一致，比较两个主语，补出谓语动词”的原则，比较的对象是studying SAT这件事，而且是一般现在时，所以补出谓语动词am，而A/B/C的was, were, are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 car in the parking lot is more warmer than is the car outside the parking lot.
A. NO CHANGE
B. are
C. was
D. were
解析：通过题中的than看出是比较平行的考点， 根据“谓语内容一致，比较两个主语，补出谓语动词”的原则，比较的对象是停车场是否暖和这件事，而且是一般现在时，所以补出谓语动词is；又根据“当第二个主语过长，常常把助动词放在第二个主语前”的原则，than后面的第二个主语由outside the parking lot修饰，所以助动词is提前到主第二个主语the car前面，所以B/C/D的are, was, were均不符合句意，所以排除B/C/D选项，所以选A。
题目检测 4
They occupied significantly more leisure time work in the park than the work time of those not required to work. 
A. NO CHANGE
B. than did zookeepers who were
C. than hours worked by zookeepers
D. compared with zookeepers 
解析：通过题中的than看出是比较平行的考点， 根据“谓语内容一致，比较两个主语，补出谓语动词”的原则，比较的对象是占用闲暇时间这件事，而且是一般过去时，所以补出谓语动词did；又根据“当第二个主语过长，常常把助动词放在第二个主语前”的原则，than后面的第二个主语由who were not required to work修饰，所以助动词did提前到主第二个主语zookeepers前面，所以A/C/D均不符合上述原则，所以排除A/C/D选项，所以选B。