求助解析英语复合句1.The practice of dwelling on the private lives of

求助解析英语复合句
1.The practice of dwelling on the private lives of celebrities leads people to pay more attention to these matters than they otherwise would.
2.Those who watch news and educational program can learn many new things while those who watch primarily entertainment shows may come to believe that most people in the world possess great wealth and good looks.
在阅读和听力中遇见以上2句句型的句子,怎么去理解?
3.The charming lady happens to be John's sister.
句中 to be 做什么成分?
4.I have not seen her for ages,i miss her.= Not having seen her for ages,i miss her?
哪种句型常用?
5.The sun setting,the cowboys rode back to the ranch.
句中setting 为什么不能改成 set?
第三句对了，固定搭配，1和2没有解析，4和5我书上是用逗号，所以不理解，希望有更多人回复。