_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .
in t_ e c_ _ e of p_ _ _ _ _ _ e f_ _ _ _ _ _ k t_ e r_ _ _ _ _ _ e of t_ e s_ _ _ _ m is to c_ _ _ _ e t_ _ t v_ _ _ _ _ _ e e_ _ n m_ _ e in t_ e s_ _ e d_ _ _ _ _ _ _ _ .
in the ca_ e of po_ _ _ _ _ e fe_ _ _ _ _ k the re_ _ _ _ _ e of the sy_ _ _ m is to ch_ _ _ e th_ t va_ _ _ _ _ e ev_ n mo_ e in the sa_ e di_ _ _ _ _ _ _ .