“…From the condition and applying the comparison Theorem [7 ] it yields From (5.3) at (5.8) From the condition and (5.6) , at (5.9) From (5.5),(5.8) and(5.9), we get From (5.2) ,we get (5.10) Then from the condition ,(5.4) , (5.6) and (5.10), we get at which leads to a contradiction ,then it must be holds ,provided that Therefore the zero solution of (1.1) is practically equistable.…”