复合名词和作为一个整体的词组在最后一个词的词尾后加-'s
a dog and cat's life
my brother-in-low's friend
以-s结尾的复数名词作为名词修饰语表示类别时,-s之后可加-'也可不加
Shanghai Teachers University
并列名词表示各自的所有关系时,要在各个名词之后加-'s
John's, Mary's and Jack's books(各自的关系)
John, Mary and jack's books(三人共有的书)
"名词词组+同位语"构成属格时,-'s放在同位语名词之后
I saw Tim at his friend Clara's.
在for...'s sake习语中,以清辅音[s]结尾的名词,为了使读音和谐,往往只加-'或连-'都省略