                                                    637

      Wu.   ( -
, )         . -
   ,      
,    .  ,  
       ,   
          ,
      .  ,  
      .

 

 ,        , 
        
'.       
  ().    ,  
  .     , 
    .    
 ,     .     
        -
 ,         -
.           -
.     ,       -
       .   
 ,       .

          .
        , .. 
   - ,      -
   . ,      
    .  ,     
    .   -    (closing
sale),          .
 ,      ,  
 .

       -
   . ,       -
    .      -
 (closing purchase) ,    ,    -
    .

    
   

         . 
    100   Widget    $50, -
    2  1      ,  
  200   $25.     ,   -
         .   
       (      -
),          
    .

        ,
  2.           -
  . ,      Widget -
 ,  Widget    $4   .