     

                                                5                                       

                           

                                                           25%        60% ~ 80%    1/3                                                                          

1986                                                                                                PCA                      

                      

                                                                                                  

                    （ ）            （ ）             《          》   

       

1.        

2.           

3.        

4.     

5.     

6.    

                                  
                                                              