192  5.    

EREW (    )
________                       ^

   >^  ^g
   

   j] ,   ^ g
  

ERCW (    )

_    .                |
   >            |   




_,    _                      _
    >             ^   D

CREW (    )

I           II           l

_    .                 
                     




        |                 _    _
    *                D

CRCW (    )

.-,    .                      _
    >             >    




_,    _                      _    _
   >             >   D

. 5.4.   EREW, CREW, ERCW  CRCW