(IP-ADV 
  (NP-SBJ 
    (-NONE- *pro*))
                    
  (VP 
    (VV 失去)
                    
    (NP-OBJ 
      (NN 妈妈))))
                    
(NP-SBJ 
  (PN 他))
                    
(VP 
  (ADVP 
    (AD 很))
                    
  (VP 
    (VA 难过))))
argm: 
                    失去 妈妈          
                
arg0: 
                    他          
                
argm: 
                    很