逻辑主语：是非谓语动词动作的执行者或承受者;它们在逻辑上存在着主谓关系或动宾关系，但不能直接作非谓语动词的主语，因此叫逻辑主语。

逻辑主语的判断：

1. 句子主语就是非谓语动词的逻辑主语，它们之间是逻辑上的主谓关系或动宾关系。例如：

She likes helping others .(she 就是 helping 的逻辑主语)

Moved by my words, her father told me the truth. (her father 是 moved 的逻辑主语)

2. 介词of 或for的宾语就是非谓语动词的逻辑主语。例如：

It”s kind of you to tell me the news . (you 是to tell 的逻辑主语)

这个句子中，it是形式主语，句子的真正主语是to tell me the news.

It is impossible for you to finish so much work in so short a time . (you 是to finish 的逻辑主语)

3. 复合结构中的宾语就是非谓动词的逻辑主语。例如：

The doctor asked me to answer her question. (me 是to answer 的逻辑主语)

I saw him playing at the river side. (him 是playing 的逻辑主语)