英语语法中的主语有多种形式，包括单数主语（如"The cat is sleeping"），复数主语（如"The cats are sleeping"），不定式短语作为主语（如"To learn English is important"），以及从句作为主语（如"What you said is true"）。熟练掌握这些主语形式有助于更好地理解英语语法，提高英语水平。
单数主语
单数主语是指一个人、物或概念。它们用单数形式的动词来表达。
| 主语 | 动词 | | --- | --- | | The cat | is sleeping. | | John | likes pizza. | | Knowledge | is power. |
复数主语
复数主语是指两个或多个人、物或概念。它们用复数形式的动词来表达。
| 主语 | 动词 | | --- | --- | | The cats | are sleeping. | | John and Mary | like pizza. | | Books | are knowledge. |
不定式短语作主语
不定式短语是由不定式和它的修饰语构成的短语。它们可以用作主语。
| 主语 | 动词 | | --- | --- | | To learn English | is important. | | To be or not to be | is the question. | | To travel | is to live. |
从句作主语
从句是一个包含主语和谓语的句子，它可以作为另一个句子的主语。
| 主语 | 动词 | | --- | --- | | What you said | is true. | | Whether he comes or not | is uncertain. | | That he is late | is not surprising. |
