动态sql多条件查询，如何拼接？

Question

下面这条sql怎么用动态sql拼接，主要是and和or那一块

SELECT *
FROM t LEFT JOIN l ON t.usernum = l.usernum AND t.date = l.date 
WHERE
    t.date = '2020-08-29'
    -------------------------------------------
    <if test="  age != '' and   age != null ">
            and t.age = #{age}
        </if>
    -------------------------------------------
    AND (( t.math > 80 OR t.english > 80 ) 
        OR ( t.pe > 90 OR t.politics > 90 ) 
        OR t.status = '1' 
        OR t.class = '三班' 
        OR l.usernum >10)
    -------------------------------------------

例如A不为空则执行t.math那段，B不为空则执行t.pe那段，C不为空则执行t.class那段，一直到结束...

<if test="  A != '' and   A != null ">
            t.math > 80 OR t.english > 80
</if>
<if test="  B != '' and   B != null ">
            t.pe > 90 OR t.politics > 90
</if>