age〈19 and total〉285 and mark 1=100 or mark2=100 or mark 3=100 age〈19 and total〉285 or mark 1=100 or mark2=100 or mark 3=100 age〈19 and total〉285 and(mark1=100 or mark2=100 or mark 3=100) (age〈19 or total〉285)and(mark1=100 o rmark2=100 or mark 3=100)