(IP 
  (NP-SBJ 
    (-NONE- *pro*))
                    
  (VP 
    (VV 证明)
                    
    (IP 
      (NP-TMP 
        (NT 当时))
                    
      (NP-SBJ 
        (NN 宫女))
                    
      (VP 
        (ADVP 
          (AD 如何))
                    
        (VP 
          (VV 极尽巧思)
                    
          (PU ，)
                    
          (VV 自得其乐))))))
arg0: 
                    宫女 
                
argm: 
                    如何 
                
argm: 
                    当时