(IP 
  (NP-SBJ 
    (PN 这))
                    
  (VP 
    (VC 是)
                    
    (NP-PRD 
      (CP 
        (WHNP-1 
          (-NONE- *OP*))
                    
        (CP 
          (IP 
            (NP-SBJ 
              (NN 人类))
                    
            (VP 
              (ADVP 
                (AD 有史以来))
                    
              (QP-ADV 
                (OD 首)
                    
                (CLP 
                  (M 次)))
                    
              (VP 
                (VRD 
                  (VV 预报)
                    
                  (VV 到))
                    
                (NP-OBJ 
                  (-NONE- *T*-1)))))
                    
          (DEC 的)))
                    
      (NP 
        (NN 太阳系)
                    
        (NN 天体))
                    
      (NP 
        (ADJP 
          (JJ 重大))
                    
        (NP 
          (NN 碰撞)))
                    
      (NP 
        (NN 现象)))))
arg0: 
                    人类 
                
arg1: 
                    *T*-1 
                
argm: 
                    首 次 
                
argm: 
                    有史以来