18．(8分)

(1)                         

   (2)                          

   (3)                                                                         

   (4)                                                                       

17．(8分)                           (1)

  (2)                               

(3)                       

(4)                                

                                                                      。

③                          

  16．(8分)

(1)                            

(2)          

(3)          

(4)①              ②                                                   

  15． (1)               (2)                          (3)

  14．                                                 

  13．