分号的主要用法有以下几种情况：
1. 用于连接两个具有独立意义但又关联紧密的句子。例如：I am studying for my exams; I need to pass them.
2. 用于连接具有长句子结构的句子成分，以增加句子的清晰度。例如：The project requires careful planning, including conducting market research; designing the product; and implementing marketing strategies.
3. 用于连接一系列具有并列结构的短语或独立动词。例如：I enjoy playing tennis; swimming; and hiking.
4. 用于在句子中插入解释、强调或相似的内容。例如：John's favorite dessert is chocolate cake; however, he also enjoys eating ice cream.
5. 用于在句子中分隔列举时具有特殊意义的词组或名词。例如：The conference will be attended by experts in various fields: medicine, law, and technology.
需要注意的是，分号不应用于连接主语和谓语动词或连接主句与从句。在这些情况下，应该使用逗号或其他标点符号。
