已知x代表某个百分制成绩，下列程序段用于显示对应的五级制成绩，正确的是( )
A．If x＞=60 Then Print"及格" Else If x＞=70 Then Print"中" Else If x＞=80 Then Print"良" Else If x＞=90 Then Print"优" Else Print"不及格" End If
B．If x＜90 Then Print"良" Else If x＜80 Then Print"中" Else If x＜70 Then Print"及格" Else If x＜60 Then Print"不及格" Else Print"优" End If
C．If x＞=90 then Print"优" Else If x＞=80 Then Print"良" Else If x＞=70 Then Print"中" Else If x＞=60 Then Print"及格" Else Print"不及格" End If End Select
D．Select Case x Case x＞=90 Print"优" Case x＞=80 Print"良" Case x＞=70 Print"中" Case x＞=60 Print"及格" Case Else Print"不及格"