网友的问题逐个解答如下：

5. It's impolite of you to visit someone without telling him in advance.

其中 impolite to visit是形容词短语吗to visit修饰系表结构吗（我翻老师们以前的回答看到的概念），还是直接it是形式主语呢，adj+不定式和形式主语这两种情况怎么区分呢。

—— it 是虚拟主语（dummy subject），它不是形式主语，没有任何替代，只是用来引出句子。英语习惯上喜欢用一个“虚拟主语” It 开头引出句子，而句子的真正主语和重心是在句子的后面，以体现语义的“尾重原则”。例如，下列结构中，it  都是虚拟主语，不是形式主语：

It is kind of you to help us. = You are kind to help us.

It seems/appears that Frank lost his temper. 

It says in the newspaper that the concert was cancelled.

这才是形式主语：It is necessary to study English.

关于It is adj. of sb. to do sth. 结构分析，详见：

https://www.cpsenglish.com/article/129

6. It is important to have your eyes examined regularly to check for any sing of eye disease.

这里it是不是形式主语to have your…是真正主语，to check的逻辑主语是什么呢，to check是不是目的状语。Check for是构成及物动词吗，还是to check/for…

——it是形式主语，to have your…是真正主语。to check的逻辑主语也是to have的逻辑主语，被省略掉，应为you。不定式to check...是to have your eyes examined regularly的目的状语，for any...则是check的目的状语。

7. There is a tradition in our office that when it’s somebody’s birthday,they bring in a cake for us all to share.

请问这里in our office是作状语还是tradition的定语？bring in是构成及物动词吗，for us all是状语修饰bring还是cake定语（我感觉状语合适），to share是修饰bring的目的状语吗？

——之前解答过，there be 存在句中常含有地点状语，in our office就是地点状语。bring in中，in 是副词小品词，bring 是及物动词。for us all to share 为不定式复合结构作cake 的定语。因为share 缺少宾语，其实宾语就是 cake。这就是作定语的特征，动宾关系的定语，属于反射不定式作定语的类型。

8. What’s the point of helping him if he doesn’t make an effort to help himself.

请问这里面to help him的逻辑主语是effort还是he呢，这种无生命的effort可以是逻辑主语吗，to help himself作什么成分?

——to help himself 是make an effort的目的状语，逻辑主语是句子主语。

9. He would never give up wanting to be a director.

其中give up是及物动词吗，wanting to be a director是什么成分，这个句子怎么分析呢?

—— give up 是及物动词，整个动名词短语wanting to be a director作宾语。动名词短语中还可以细分，to be a director为wanting 的宾语。