Teacher （Ton，Tname, Tage, Tsex); Department（Don，Dname, Tno); Work (Tno, Dno, Year, Salary)
假设Teacher 的Tno属性、Department 的Dno属性以及Work 的Year 属性上有B+树索引，说明下列查询语句的一种较优的处理方法。
(1) selecl * from teacher where tsex ='女＇
(2) select * from department where dno < 301
(3) select * from work where Year <> 2000
(4) select * from work where year> 2000 and salary < 5000
(5) select * from work where year < 2000 or salary < 5000
