. (只有月和年，就不
必加逗号)
2.2.10 逗号用以分开地名、省名、国名、街道名、巷弄名等：
1. linda lives at 1234 amarillo ave., #1, palo alto, ca 94303, u.s.a.
2.2.11 逗号用在 such as 和 especially 的前面：
1. they enjoy outdoor sports, such as hiking and riding.
2. he likes all extracurricular activities, especially basketball
playing.
2.3 突出句子中某个插入成份(parenthetical elements):
所谓插入成份，是指在句子中去掉它也可成立的成份。插入成份一般是感叹词、状语、副词子句等。
2.3.1 句子里插入的词、短语、子句等,加上逗号以示插入成份：
1. he knew, however, that no one would listen to his warning. ( 插入
however)
2. no, you may not come with us. (插入 no)
2.3.2 用逗号分开“乃此非彼”的结构：
1. jane, not shirley, will attend the meeting. (是 jane，不是 shirley)
2. he wanted to see mr. wu, not mr. hu. (是吴先生，不是胡先生)
3. some say the world will end in ice, not fire. (是冰，不是火)
4. it was her money, not her charm or personality, that first attracted