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、标点符号
1. 含义：
句中的标点符号使用要规范。
2. 类型：
(1) 所有格符号
3. 用法
(1) 表示名词和不定代词的所有格。冠词和一般名词复数加 ’s。
例句1: The boy’s mother is our school teacher.
解析：本句中的boy前面有冠词the为单数名词，所以加’s。
例句2: A civil engineer’s skills are needed to operate this machinery.
解析：本句中的civil engineer前面有冠词a为单数名词，所以加’s。
例句3: People’s opinions were heard by the president of this party.
解析：本句中的people为一般名词复数，所以加’s。
例句4: Children’s laughter filled the corridor.
解析：本句中的children为一般名词复数，所以加’s。
(2) 复数名词加s’。
例句5: Birds’ immigration normally occurs in winter.
解析：本句中的birds为复数名词，所以加s’。
(3) 人名以s结尾的加s’。
例句6: Douglas’s crimes were investigated by two detectives.
解析：本句中的Douglas以s结尾，所以加s’。
(4) 修饰语前不加所有格。
例句7: There is a boy’s interested in studying a science course.（错误）
解析：interested in studying a science course作为boy的修饰语，前面需要是名词形式，而不能加所有格，所以改法如下：
例句8: There is a boy interested in studying a science course.
题目检测
题目检测 1
An aerospace engineers skills’ are applicable to areas beyond space exploration.
A. NO CHANGE
B. engineer’s skills
C. engineers’ skills
D. engineers skill’s
解析：通过所有格看出是标点符号的考点，根据“冠词和一般名词复数加 ’s”的原则，an aerospace engineer应该是单数，后加’s，所以排除A/C/D，所以选B。
题目检测 2
The question now is whether training more hospitalists will really improve patients quality of care. 
A. NO CHANGE
B. patients's quality 
C. patient's quality 
D. patients' quality 
解析：通过所有格看出是标点符号的考点，根据“复数名词加s’”的原则，patients为复数名词，所以后面直接加s’；而如A项不加所有格、B项复数再加’s和C项单数加’s，均为错误选项故排除A/B/C，所以选D。
题目检测 3
The Stevens’s house had a family reunion where they saw some relatives they hadn't seen for 20 years. 
A. NO CHANGE
B. The Steven’s house 
C. The Stevens house
D. The Stevens’ house
解析：通过所有格看出是标点符号的考点，根据“人名以s结尾的加s’”的原则，Stevens为人名，所以后面直接加’s；而如C 项不加所有格和B、D拆开Stevens为Steven的形式，均为错误选项故排除B/C/D，所以选A。
题目检测 4
The student union depends on group leaders’ to keep it running on schedule.
A. NO CHANGE
B. leader’s
C. leaders 
D. leaders’s
解析：通过所有格看出是标点符号的考点，根据“修饰语前不加所有格”的原则，to keep it running on schedule修饰leaders，所以leaders不加所有格形式，故排除A/B/D，所以选C。