b1.mark = '<?php echo $before_last_mark ?>' and b2.mark= '<?php echo $last_mark ?>' and
ABS(b2.timeuser - b1.timeuser) < 100
order by diff desc;
b1.mark = '<?php echo $before_last_mark ?>' and b2.mark= '<?php echo $last_mark ?>' and
ABS(b2.timeuser - b1.timeuser) < 100
order by diff desc;