读读下列句子，哪里不恰当，请改正过来。   
1．王丹同学端正了学习目的。  
                                                                                                                                                  
2．这里的风景真动听。    
                                                                                                                                                
3．爱迪生是世界上闻名的著名科学家。     
                                                                                                                                               
4．科学知识是永远一辈子学不完的。