=IF(C11>=90,"优秀",IF(AND(C11>=80,C11<90),"良好",IF(AND(C11>=70,C11<80),"中等","及格")))
=if(B1>=90,"优秀",if(B1>=80,"良好",if(B1>=70,"中等","")
=LOOKUP(A1,{70,80,90},{"中等","良好","优秀"})
