A:隋唐科举制发展
B:唐朝民族关系和谐
C:宋代市民文化丰富
D:明清工商业繁荣
设m∈R,则“m<1”是“方程x2+x+m=0有实数根”的( )条件
Though he started late, Mr.Guo played the piano as well as, if________, Miss Liu.