(IP 
  (NP-SBJ 
    (PN 大家))
                    
  (VP 
    (CC 既)
                    
    (VP 
      (PP-BNF 
        (P 为)
                    
        (NP 
          (PN 他们)))
                    
      (VP 
        (VV 惋惜)))
                    
    (PU ，)
                    
    (CC 又)
                    
    (VP 
      (VV 觉得)
                    
      (IP-OBJ 
        (NP-SBJ 
          (PN 这))
                    
        (VP 
          (VC 是)
                    
          (NP-PRD 
            (QP 
              (CD 一)
                    
              (CLP 
                (M 个)))
                    
            (CP 
              (WHNP-1 
                (-NONE- *OP*))
                    
              (CP 
                (IP 
                  (NP-SBJ 
                    (-NONE- *T*-1))
                    
                  (VP 
                    (ADVP 
                      (AD 非常))
                    
                    (VP 
                      (VV 值得)
                    
                      (NP-OBJ 
                        (NN 忧虑)))))
                    
                (DEC 的)))
                    
            (NP 
              (NN 问题))))))))
arg0: 
                    大家 
                
arg1: 
                    为 他们