我想做一个学习成绩考核表，为什么总不成功，帮我看看是什么地方出了问题

Private Sub Command1_Click()
Dim a As Integer
Dim b As Byte
a = tetFen.Text
b = tetPenlun.Text
If a >= 90 Then
b = "良"
ElseIf a >= 80 Then
b = "优"
ElseIf a >= 70 Then
b = "秀"
ElseIf a >= 60 Then
b = "及格"
Else
b = "不及格"
End If
End Sub

Private Sub Form_Load()
tetFen.Text = ""
tetPenlun.Text = ""
End Sub

你定义的b是要来用什么的?如果是要保存"优","良"这些中文字的话把b定义成String就行啦,
这样很容易出现类型不匹配的情况的

你没有显示语句啊
Private Sub Command1_Click()
Dim a As Integer
Dim b As Byte
a = tetFen.Text
b = tetPenlun.Text
If a >= 90 Then
b = "良"
ElseIf a >= 80 Then
b = "优"
ElseIf a >= 70 Then
b = "秀"
ElseIf a >= 60 Then
b = "及格"
Else
b = "不及格"
End If

msgbox b
End Sub

Private Sub Form_Load()
tetFen.Text = ""
tetPenlun.Text = ""
End Sub

一个简单的错误,定义了变量b,你就b = tetPenlun.Text,意思是tetPenlun.Text里的值赋给b,把你不觉得奇怪吗,应该改为:
Private Sub Command1_Click()
Dim a As Integer
Dim b As String
a = tetFen.Text

If a >= 90 Then
b = "良"
ElseIf a >= 80 Then
b = "优"
ElseIf a >= 70 Then
b = "秀"
ElseIf a >= 60 Then
b = "及格"
Else
b = "不及格"
End If
tetPenlun.Text = b
End Sub

Private Sub Form_Load()
tetFen.Text = ""
tetPenlun.Text = ""
End Sub
判断之后,再把b值指向文本框就ok了,

楼上正解