关于动名词作主语的用法，综合权威资料整理如下：

一、动名词作主语的基本规则

基本结构

动名词短语（如Swimming, Reading）可直接作句子主语，例如：

- Swimming is a good sport.

- Reading is enjoyable.

谓语动词形式

动名词作主语时，谓语动词用单数形式，例如：

- The problem lies in communication.

特殊结构

当动名词短语较长时，常用it作形式主语，将真实主语置于句尾，例如：

- It's important to protect the environment.

二、动名词作主语的常见用法

直接作主语

- Smoking is prohibited here.

- Climbing mountains is really fun.

- Listening to music is beneficial.

动名词作宾语

动名词可作及物动词的宾语，例如：

- I enjoy painting.

- The company is engaged in research.

动名词作表语

动名词可作系动词（如be, seem）的表语，例如：

- The movie was fascinating.

- The task seemed overwhelming.

三、易混淆点与注意事项

it作形式主语

- 真实主语为动名词短语，需用it替代，例如：

- It's no use waiting.

- It's foolish to ignore the problem.

- 形式主语后通常接that从句，但that可省略，例如：

- The fact that he missed the meeting surprised everyone.

动名词与不定式作主语的对比

动名词作主语时，谓语用单数；不定式作主语时，谓语根据后续动词形式决定（如do/does）。例如：

- Reading is good for health.

- To read is to learn.

四、典型错误示例

谓语动词错误：

*Swimming is good for your healthy.*（应为"health"为名词，此处需用动名词"doing"）

逻辑错误：

*He likes to do his homework every day.*（应使用动名词"doing"作主语）

通过以上规则和示例，可系统掌握动名词作主语的用法。建议结合具体语境练习，注意区分动名词与不定式、分词等非谓语动词的差异。