(IP 
  (ADVP 
    (AD 然而))
                    
  (PP-TMP 
    (P 当)
                    
    (NP 
      (CP 
        (WHNP-1 
          (-NONE- *OP*))
                    
        (CP 
          (IP 
            (NP-SBJ 
              (PN 他们))
                    
            (VP 
              (NP-TMP 
                (-NONE- *T*-1))
                    
              (VP 
                (VV 购买)
                    
                (NP-OBJ 
                  (NN 物品)))))
                    
          (DEC 的)))
                    
      (NP 
        (NN 时候))))
                    
  (PU ，)
                    
  (NP-SBJ 
    (-NONE- *pro*))
                    
  (VP 
    (ADVP 
      (AD 却))
                    
    (ADVP 
      (AD 从来))
                    
    (ADVP 
      (AD 不))
                    
    (VP 
      (VV 讲价))))
arg0: 
                    *pro* 
                
argm: 
                    不 
                
argm: 
                    从来 
                
argm: 
                    却 
                
argm: 
                    当 *OP* 他们 *T*-1 购买 物品 的 时候 
                
argm: 
                    然而