1. 逗号使用3规则：
1). 使用逗号来分开插入从句和短语;
例如：
Gordon, who is a writer by profession, bakes an excellent cheesecake.
2).用逗号分开系列成分。如果有2个以上相同成分，则应用逗号分开;
例如：
My recipe for buttermilk biscuits contains flour, soda and buttermilk.
3).在引导性分词或介词短语后使用逗号;
例如：
After the banquet, Harold and Martha went dancing.
4).利用逗号来分开连词连接的独立从句。
例如：
Susan’s old car has been belching blue smoke from the tailpipe for two weeks, but it has not broken down yet.
2.分号使用两大规则：
1) 使用分号而不是并列连词来连接两个含义紧密的独立从句;
例如：
Whooping cranes are an endangered species; they are unlikely to survive if we continue to pollute.
2)therefore、nevertheless和moreover等词连接的独立从句可用分号隔开。
(sat)例如：
The staff meeting has been postponed until next Thursday; therefore, I will be unable to get approval for my project until then.
3.冒号使用3大规则：
1).在正式的写作中，冒号的作用仅在于表明其后是对前面所述内容的详细说明、定义、解释或过去发生事情的概述。冒号之前一般是独立从句，并且通常情况下有as follows、the following、namely或like等提示短语。
例如：
正确：Your instructions are as follows: read the passage carefully, answer the questions on the last page, and turn over your answer sheet.
2).动词和直接宾语间不要放冒号。
例如：
错误：I want: a slice of pizza and a small green salad.
正确：This is what I want: A slice of pizza and a small green salad.
3).如果前后两句话有如上所述的紧密关系，即使没有上述表示这层关系的短语，也可使用冒号，并且在这种情况下，句号也可用。
例如：
正确：We were aghast: The “charming country inn” that had been advertised in such glowing terms proved to be a leaking cabin full of mosquitoes.