using case in plsql part2

DECLARE
grade number :=100;
BEGIN

 CASE
 
   when (grade >= 75) then             dbms_output.put_line('Excellent');
   when grade <=75 and grade >=60 then dbms_output.put_line('Very good');
   when grade <=60 and grade >=50 then dbms_output.put_line('Well done');
   when grade <=50 and grade >=40 then dbms_output.put_line('You passed');
   when grade <=40 and grade >=35 then dbms_output.put_line('Better try again');
   else dbms_output.put_line('No such grade');
   END CASE;

END;